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Un dee symboles sulvants apparaltra sur la darnlAre image de cheque microfiche, seion la cas: la symboie -^ signifie "A SUIVRE ", ie symbola V signifie "FIN ". Maps, plates, charts, etc., m»y be filmed at different reduction ratios. Those too large to be entirely included in one exposure are filmed beginning in the upper left hand corner, left to right and top to bottom, aa many frames as required. The following diagrams illustrate tha method: Les cartas, planches, tableaux, etc., peuvent fttre fiimAa A das taux de reduction dIffArents. Lorsque ie document est trop grand pour dtre reproduit en un aaui cllchA, II eat film* A partir da i'angle sup6rieur gauche, de gauche d droite, et de haut en baa, an pranant la nombre d'Imagaa nAcaaaaira. Les diagrammes suivants iliustrant la mAthode. 1 2 3 1 2 3 4 5 6 PLANT LIFE tTbc Xibrars oX TH0c<:ul fkwovclc^gc Civtii, One Shilling net, each. ARCHITECTURE. By P. L. Waterhouse. PLANT LIFE. By GRANT Al.LEN. THE STARS. By G. F. CHAMBERS. F.R.A.S. FOREST AND STREAM. By jAMES RODWAY. THE MIND. By PROF. J. M. Baldwin. THE RELIGIONS OF THE V/ORLD. By the Rev. E. D. Price, F.G.S. LONDON : HODDER AND STOUGHTON PLANT LIFE BY GRANT ALLEN WITH FORTY-NINE ILLUSTRATIONS HODDER AND STOUGHTON PUBLISHERS LONDON I.P OjkbO ' rl^j'^ ^'^^'t I I; 15- ^ a a a tl ai g' tl in tii cc de th tic vi 0l( It f< I i"r- PREFACE r HA n endeavoured to give a short and suooirot account of the principal phenomena of plant life, in language suited to the comprehension of unscientrfic readers. As far as possible I have avoided technical terms and minute detail, while I have tripd w adopt a more philosophical tone than IS vtu-^ily fimpioyed in elementary works. - t•■^ - ireibtjd my voadors, not as children, but fi.3 cr.ba auj wrmor-, endowed with the avorigs amount of intellip eac^ and insight, and anjT'.jag to rMm: some sensible information about .he world of plrnts which exists all round them Acting upon this basis, I have freely admitted the main results of the latest investi- gallons, accepting throughout the evolutionary theory, and makin- the study of plants a first introduction to the great modern principles of here<1.ty, variation, natural selection, and adapta- tion to the environment. Hence I have wasted comparatively little space on mere structural detail, and have dwelt as much as possible on those more interesting features in the interrela- tion of_ the plant and animal worlds which Uuve vmfled .or us of late years the dry bones of the old technical botany. My principle has been to unfold my subject 6 PBBFAOl by gradual stages, telling the reader oae thing at a time, and building up by degrees his know- ledge of the subject. My treatment is, ther-sfore, to some extent diagrammatic, especially in the earlier chapters ; but I endeavour as I proceed to correct the generalisations and fill in the gaps of the first crude statement. I have even made bold enough to speak at times of " carbonic acid," where I ought strictly to have said "carbon dioxide," and to glide gently over the distinction between hydro- carbons and carbo-hydrates, which would interest none but medical students. I have 'been well content to make these trivial sacrifices of formal accuracy in order to find room for fuller -exposition of the delightful relations between flowers and insects, birds and fruits, soil and plant, climate and foliage. In one word, I have dwelt more on the functions and habits of plants than on their structure and classification. At the same time I have tried to lead on my reader by gradual stages to the further study of plants in the concrete ; and I shall be disappointed if my little book does not induce a considerable proportion of those into whose hands it may fall to pursue the subject further in our fields and woods by the aid of a Flora. G. A. The Croft, Hindhbad. CONTENTS :ntroductoiit CHAPTER I PAOB 9 CHAPTER II HOW PLANTS BKOAN TO UK H CHAPTER III now PLANTS CAME TO DIFFER FROM ONE ANOTHER 26 CHAPTER IV HOW PLANTS EAT • • • . 85 CHAPTER V HOW PLANTS DRINK 67 CHAPTER VI HOW PLANTS MARRY ^ »g CHAPTER VII VARIOUS MARRIAGE CUSTOMS 93 8 OONTMNTl OHAPTKIi VIII MAnnUdl 0U8T0M1 • • WAQU . IIS CHAPTER IX Tnr WIND Ai oAnniRR . 185 CHAPTER X HOW rLOWEM CLUa TOOETUKn , . , , .117 CflAPTKR XI WHAT PLANTS DO FOR TIIKIR VOUNO • ClIAPTliU XU THE •lEM AND BRANCHEH . . 162 . 176 CHAPTER XIII SOME PLANT LFOnnAl'IIlKH ...... IJJQ ^ CHAPTER XIV 'illK PAST HI8T0KY OF PLANTS . • • . 221 91 18 i CHAPTER I. iNTRODUOTOIif . I FROPOSB In this volume to write brioi the history of plants, their origin and wheir develop, mont. I shall deal with them all, both bi.^ and iittle, from the cedar that is in Lebanon to the hyssop thai epringeth out of the wall. I shall endeavour to show how they first cam') into existence, and by what slow degrees they have been altered and moulded into the immense variety of tree, shrub, and herb, palm, mush- room, and sea-weed wo now behold before us In short, i shall treat the history of plants much as one treats the history of a nation, beginning with their simple and unobtrusive origin, and tracing them up through varying stages to their highest point of beauty and efficiency. Plants are living things. That is the first idea we must clearly form about them. Thev are Lvisg m just the same sense that you ani I are. They were horn from a p^ed, the joint product of two previous individuals, their father and mother. Plants likewise live by eating- they have mouths and stomachs, which devour' digest, cmd assimilate the food supplied to them.' Ihese mouths and stomachs exist in the shape of leaves, whose business it is to catch floating 10 THE STORY OF THE PLANTb. particles of carbonio acid in the air around, to suck such particles in jy means of countless lips, and to extract from them the carbon which is the principal food and raw material of plant life. Plants also drink, but, unlike ourselves, they have quite different mouths to eat with and to drink with. They take in their more solid constituent, carbon, with their leaves from the air; but they take in their liquid constituent, water, with their roots and rootlets from the soil beneath them. "More solid," I say, because the greater part of the wood and harder tissues of plants is made up of carbon, in combination with other less important materials; thougn, when the plants eat this carbon, it is not in the solid form, but in the shape of a gas, carbonio acid, as I shall more fully explain when we come to consider this subject in detail. For the present, it will be enough to remember that Plants are living things, which eat and drink exactly as we ourselves do. Plants also marry and rear families. They have two distinct sexes, male and female— sometimes separated on different plants, but more often united on the same stem, or even combined in the same flower. For flowers are the reproductive parts of plants ; they are there for the purpose of producing the seeds, from which new plants spring, and by means of which each kind is perpetuated. The male portions of plants of the higher types are known as stamens; they shed a yellow powder which we call 'pollen, and this powder has a fertilising influence on the young seeds or ovules. The female portion I ^■#s»«^^ INTRODUCTORY. 11 I ^I^^t ^}''- '"«'?" *yP«« « known as the pistu; It oontams tiny undeveloped knobs or ovules, which can only sweU out and grow into fruitfu seeds providedf they have been fertilised X,P°"r ^""^ ''■^ «'*'°«°8 °f their own or some 'her flower. The ovules thus answer ve^ closely to the eggs of animals. After they ha^ been fertilised the pistil begins to mature into what we call a /mi, which is sometimes a swe^ and juioy berry, as in the grape or the currant, the "oTel""'" " ""' '=''^^"'^' "' •" '^'^ poppy 0' Plants, however, unlike animals, are usually fixed anl rooted to one spot. This mZs it of 1 t!i^' u PT'."° K^^^"^ ^ go « search of mateo, like birds or butterflies, squirrels or weasels. So they are obliged to depend upon outside agencies, not themselves, for the con- veyanoe of pollen from one flower to another Sometime, m particular plants, such as the ?in„ i',!?"'' ^■^^^•- " '^ 'he wind that carries tl^u}^" '''' ?-'"'l89 from one blossom to its sh7d tbfLtf ^' u ^^'' '=*^«' ^^^ «'^°'«'^^ which shed the pollen hang out freely to the breeze while the pistil, which is to catch it, is proS with numberless little feathery tails to^ receive the passing grams of fertilising powder But oftener still, it is insects that perf^^ tWs Wnd hf^v V^u P'^°'' ^' '" 'he dog-rose, the holly, hook, and the greater part of our beautiful garden flowers. In such cases the plant usually makes Its blossom very attractive with bright-coloured petals, so as to allure the insect, whii it reZs him for his trouble in carrying 'away the poS 13 THS BTOBY OF THB PLAMTB. by giving him in return a drop of honey. The bee Ox- butterfly goes there, of course, for the honey alone, unconscious that he is aiding the plant to set its seeds; but the plant puts the honey thsre in order to entice him against his will to transport the fertilising powder from flower to flower. There is no more fascinating chapter in the great book of hfe than that which deals with these marriage relations of the flowers and insects, and I shall explain at some detail in kter portions of this little work some of the most curious and in teres oliig of such devices. Again, after the plant has had its flower fertilised, and has set its seed, it has to place its young ones out in the world to the greatest a'lvantage.' If it merely drops them under its own branches, they may not thrive at all; it may have impoverished the soil abeady of certain thmgs which are necessary for that particular kmd, owing to causes to be explained hereafter ; and even where this is not the case, the sur- rounding soil may be so iully occupied by other plants that the poor little seedlings get no chance of eotablishing themselves. To meet such emergencies, plants have invented all sorts of clever dodges for dispersing their seeds, into the nature of which we will go in full in the sequel. Thus, some of them put feathery tops to their seeds or fruits, like the thistle and the dandeUon, the willow and the cotton-bush, by means of which they float lightly on the air, and are wafted by the wind to nev/ and favourable situations. Others, again, bribe animals to dis- perse them, by the allurement of sweet and pulpy INTRODUOTORT. 13 fruits, like the strawberry or the orange ; and in all these instances, though the fruit or outer coat IS edible, the actual seed itseh* is hard and indi- gestible, like the orange-pip, or is covered with a sohd envelope like the cherry-stone. Numerous other examples we shaU see by and by in their proper place. For the present, we have only to remember that plants to some extent provide beforehand for their children, and in many cases take care to set them out in life to the best possible advantage. Most of these points to which I am here briefly caUmg your attention are true only of ttie higher plants, and especially of land-plants. For we must not forget that plants, hke animals, difler immensely from one another in dignity rank, and relative development. There are higher and lower orders. We shall have to consider, therefore, their grades and classes— to hnd out why some are big, some small ; some annual, some perennial ; why some are rooted in dry land, while some float freely about in water • why some have soft stems Hke spinach and ce ery, while others have hard trunks like the oak and the chestnut. We shall also have to ask ourselves what were the causes which made them differ at first from one another, and to. what agencies they owe the various steps in" their upward development. In short, we must not rest content with merely saying that the rose is hke this and the cabbage like that ; we must try to find out what gave to each of them Its mam distinctive features. We nust " con- sider the lilies, how they grow," and must seek 14 THE STORY OF THE PLANTS. to account for their growth and thehr peculiari- ties. And now let me sum np again these central ideas of our future reading on plants and their history. Plants are living things ; they eat with their leaves, and drink with their rootlets. They take up carbon from the air, and water from the soil, and build the materials so derived into their own bodies. Plants also marry and are given in marriage. They have often two sexes, male and female. Each seed is thus the product of a separate father and mother. Plants are of many kinds, and we must inquire by and by how they 5ame to be so. Plants live on sea and land, and have varieties specially fitted for almost every situation. Plants have very varied ways of securing the fertilisation of their flowers, and look after the future of their young, like good parents that they are, in many different man- ners. Plants are higher and lower, exactly like inimals. These are some of the points we must proceed to consider at greater length in the following pages. CHAPTEB II. HOW PLANTS BEGAN TO BE. Which came first — the plant or the animal ? That question is almost as absurd as if one were to ask, Which came first — the beast of prey, or the animals it preys upon? Clearly, HOW PLANTS BEGAN TO BE. 15 tne earliest animals could not possibly have bee; lions and timers; for lionb and tigers could not begin to exist till after there were deer and Mitelopes for them to hunt and devour. Now the general connection between animals and plants is somewhat the same in this respect as the general connection between bwasts of prey and the creatures they feed upon. For aU animah feed, Tirectly or indirectly, upon plants and their products. Even carnivorous animals eat sheep and rabbits, let us say ; but then, the sheep and the rabbits eat grass and clover. In the last resort, plants are self- supportxng; animals feed upon what the plants have laid by for their own uses. Every animal gets all its material (except water) directly or indirectly from plants. In one word, plants are the only things that know how to manufactv/re hvtng material. Roughly speaking, plants are the producers and animals the consumers. Plants are like the pine-tree that makes the wood; animals are like the fire that bums it up and reduces it to Its previous unorganised condition. It is a little difficult really to understand the true relation of plants and animals without some small mental effort; yet the point is so important, and will help us so much in our after inquiries that I will venture upon asking you to make that effort, here at the very outset. ^ If you take a piece of wood or coal, you have m It a quantity of hydrogen and carbon, almost unmixed with oxygen, or at least combined with far less oxygen than they are capable of uniting 16 THE 8T0RT OP THE PLANTS. ■f, with. Now put a light to the wood or coal, and what happens ? Tney catch fire, as we say, and burn till tney are consumed. And what is the meaning of this burning ? Why, the carbon and hydrogen are rushing together with oxygen — taking up all the oxygen they can unite with, and forming with it carbonic acid and water. The carbon joins the oxygen in a very close embrace, and becomes carbouic acid gas, which goes up the chimney and mikos vith the atmosphere ; the hydrogen joins the oxygen in an equally intimate union, and similarly goes ofif into the air in the form of steam or watery vapour. Burning, in fact, is nothing more than the uaion of the carbon and hydrogen in wood or coal with the oxygen of the atmosphere. But observe that, as the carbon and hydrogen bum, they give off light and heat. This light and heat they held stored up before in their separate form; it was, so to speak, dormant or latent within them. Free carbon and free hydrogen contain an amount of energy, that is to say of latent light and dormant heat, which they yield up when they unite with free oxygen. And though the carbon and hydrogen in wood and coal are not quite free, they may be regarded as free for our present purpose. Now, where did this light and heat come from? Well, the wood, we know, is part of a tree which has grown in the open air, by thft aid of sunshine. The coal is just equally part of certain very ancient plants, long pressed beneath the earth and crushed and hardened, but still possessing the plant-like property of burning )r coal, and NQ say, and 7hat is the carbon and I oxygen- unite with, Eind water, very clos9 gas, which vith the oxygen in rly goes ofif or watery more than in wood or here. But ogon bum, light and lir separate i or latent I hydrogen I to say of they yield gen. And wood and Bgarded as heat come part of a by thft aid Qy part of ed beneath 1, but still jf burning HOW PLAWT8 BEGAN TO BE. I7 r'rJJg!^^^: In both cases the light The Bunlhlue'lMuJ^tt storehouse of energy, oak-tree or or the vi' ''T' °^ '^^ """^e™ which oinstitute coal Ir, J ""'">"*, "'"b-mosseB carbon from the oxLon T"""^^^.'" *h«'" *e the hydroZ from?h!. °^ '""'^?'''° ^"''J. and the sap Tn earca,«?J^'" °' "*« ^'''«' i" 10689 upon the air1ni,^°''¥^° ^"^ '"^"^d carbon Ld the hydrogen rwith°""' ""^'K'^' oxygen and a few other m„i'^ ^^ ^^""y "'"e loose and almost ht. '»5'«"al8) were left in and wood of the oak or thf"?' '° ">« '^^'^^ point to which I wi^h t "'"''-'npss. But the your attenton is thTs-theTunZ-?"^ '° ''""'' used up for thfifim-. k •■S"' ^a» actually separatfonttwetn' CoxygTn "n thete"1, "^^ St r'°^ ""i' M4ro°n"theXr''"A's ind\lt'u SedTromlh""''"'?'' *« "S^' within U. not'a'TctulThght'and hJat^H^"' as ■.tt5;d suniCf"'' '"^ ''^«° welldjscrib:d wttthe'titS-rSn^^'^'-^ can.get out of the p.ant'in"C eK/^C anf Th^fhrpVt" °^hf rarfcl °' -^'• S *rtrm-- rCifCf ^^^^^^ carbonic and? T»of , "^^^ ™"ch ana/ Just as much as it iook 2 18 THE 8T0BY OF TH£ PLANTS. t originally to build that part of the plant from. SimultanoousW, other particles of oxygen in the air rush together with particles of hydrogen in the fuel, and foi-m water, in the shape of steam. How much water? Just as much as it took originally to build that part of the plant from. As they unite, they give out their dormant heat and light. How much heat and light? Just as much as they absorbed in the act of building up those parts of the plant from the sunshine that fell upon thein. In other words, the same quantity of oxygen that was first separated from the carbon and hydrogen reunites with them in the act of burn- ing, and the same amount of heat and light that were required to effect their separation is yielded up again in the act of reunion. Let us put ^his point numerically, and I will simplify it exceedingly, so as to make my meaning clearer. Suppose we begin with a particle of carbonic acid and a particle of water m the interior of p green leaf — tho carbonic acid swallowed from the air by the leaf, the water brought to it as sap from the roots. Now, under the influence of sunlight, these materials are separated into their component parts. The particle of carbonic acid consists of one atom of carbon, closely locked up with two atoms of oxygen. It takes an amount of sunlight, which we will call A, to unlock this union, and separate the atoms. The oxygen goes off free into the and the carbon remains in the leaf as air ' material for building the plant up. Again, the particle of water consists of tvro atoms of ' BOW PLANTS BEOAN TO BB. I9 KeT"'rf"'ri,"'^ '°'^'^ "P ^"''h °n« "to™ of oxygen It takes an amount of Bunlicht which tTeMon?:" Th'°"'"°'='' *'^ ""'°" a Js'ep'S tue atoms The oxygen onoe more goes olf free un?on with'i'hr'* 't' Y'T"" i°'°« '" » loos^ union with the carbon already spoken of Now burn the material resulting L£ these twoS' and what happens? Two atoms of oxveen once more unite with the one atom of carbon^to form a particle of carbonic acid ; one atom of oxygon once more unites with the two atoms of hydrogen to form a particle of water, and Xere %htTnd°h!, '." ''^ r' °' •""°" an'amoun of light and heat exactly equa to the A and H ongmally locked up in ?he act of sepratng lifJ reX"i^";n'"!'.^%" ?''■"■' ^ ''°P«' ^'"'t Pl"nt laige the elements which chiefly comoose it namely, carbon and hydrogen-exist o7yfn ver^ lor sepanting these elements from oxygon under he influenca of sunlight, and building^tl^em uj nto fresh forms, whose great peculiarity is tha^t they possess energy or dormant motion.^ animal breaks it down again, h! iT in f.,?f a Blow fire, where plant^products 1 k^ Lsse ' fruits, nuts or grains, are consumed by degrees' and reduced once more to their original cSon The animal eats ^vilat the plait laid by He 30 TBS BTORT OF THE PLANTS. also breathes^ — that is to say, takes oxygen into his lungs. Within his body that oxygen once more unites with the carbon and the hydrogen, and is given out again in union with them as carbonic acid and water. And the energy in the plant food, thus set free within his body, takes the form of animal heat and animal motion — just as the ouergy set ^^ee in the locomotive takes the form of heat and visible movement. Animals are thus the absolute converse of plants ; all that the plants did, the animal undoes again. Briefly to recapitulate this rather dry subject, — the plant is a mechanism for separating oxygen from carbon and hydrogen, and for storing up sun-energy. The animal is a mechanism for uniting oxygen with carbon and hydrogen, and for using the stored -up sun -energy as heat and motion. And now you can see why it is so absurd to ask, Which came first, the plant or the animal? You might as well ask, Which came first, the coal or the fire ? All the living material in the world was first made and laid up by plants. They alone have the power to make living or energy-yielding stuff out of dead and inert water or carbonic acid. They are the origin and foundation of life. Without them there could be no living thing in the universe. It is Ml their green parts alone that the wonderful transformation of dead matter into living bodies takes place ; they alone know how to store up and utilise the sunshine that falls upon them. HOW PLANTS BEGAN TO Bl. 31 iS All the animal can do is to take the living material the plant has made for him, and to consume it slowly in his own body. He destroys it (aa 'iving matter) just as truly as a fire does, and turns it loose on the air again in the dead and inert forms of water and carbonic acid. It is clear, then, that plants must have come first, and animals afterward. The earliest living beings must needs have boon plants— very •imple plants; yet essentially plants in this— that they were green, and that they separated carbon and hydrogen from oxygen under the influence of sunlight. It is that above vwery- fehing that makes true plants; though some degenerate plants have now given up their ancestral habit, and behave in this respect much like animals. How did the first plant of all come into bemg ? About that, at present, we know very little. We can only guess that, in the early at^es of the world, when matter was fresher and more plastic than now, certain combinations were set up between atoms under the influence of sun- light, which formed the earliest living body. This would be what is called " spontaneous generation." Whether such spontaneous genera- tion ever took place is much disputed ; though some people competent to form an opinion inoline to believe that it probably did take place m remote times and under special conditions. But it is certain, or almost certain, that in our 22 TBB BTORT OV TRF PLAMTt. ft I own daya 8,t teagt spontftneous generation does not tftko place— perhaps because all the available material is otherwise employed, perhaps because the conditions are no longer favourable. At any rate, wo have every reaHon iio suj^/ooae that at the present day every Hving being, whothor plant or animal, is the product of a previous living being, its parent, or of two previous living bemgs, its father and mother. Why bhould this be so? Well, if you Ihiuk for a moment, you will see that it results almost naturally from the other facts we have so far considered. For th^ plant is a machine for making living matter out of water and-carbouio acid, under the influence of sunlight. As long as sunlight, direct or reflected, in sun or shade, falls upon a jj? ben plant, the plant goes on taking up carbcnic acid from the air by means of its leaves, and water from the earth by means of its roots, and continues to manufacture from them fresh living material. Thus it must be always growing, as we say ; in other words, the mass of living material must be constantly increasing. Now, it results from this that the plant would grow in time unwieldily large ; a^ \ m simple types, when it grows very large, it splits or divides into two portions. That is the real origin of what we call HEPRODucTiot . In its simplest forms, reproduwlion means no more than this — that a rather 1 -["ge body, which cannot easily hold together, divides in two, and that each part of it then continues to live and grow exactly as the whole did. This seems odd and unfamiliar to you, because 111 I VMT PLANTS BSOAN fu BB. you Mre thinking of large and vor^ v.dvanQf)d plants, like a tweet-poa or a po'^ato. But you must retnembor that we are dealing hero with very early and simple plants, and that these early and simple plants consist for the most part of tiny green mites, floating free in water. They are generally invisible to the naked eye, and are in point of fact mere specks of f^een jelly Yet it ifl from such insignilitant atoms as th ^bc that the great forest tvees derive their origin, thrr.gh a long line of ancestors ; and if we wish to understand the icir^er and more developed plants, we must begm by understanding thes^ their si)nple relations. Very .^arly plants, then, boated free in water ; and there is reason to believe that for a con- siderable period in the beginnings of our woild there was no dry land at all ; the whole surface of the globe was covered by one boundless ocean. At any rate, moat of the simplest and earUeat fonns of life no'.; remaining to us inhabit the water, either fresh or salt ; while almost all the higher and nobler plants and animals are dwellers on land. Hence it i? not unreasonable to con- clude that life began in the sea, and only gradually spread itself over the islands and continents. Floating jelly-like plants would readily reach a size at which it would be convenient for them to split in two— or rather, at which it would be difiBcult for them to hold together; and most very small floating plants do to this day continue to grow, up to a certain point, and then divir^e into two similar and equal portions. This is th(» L rr 24 THE STORY OP THE PLANTS. simplest known form of what we call reprodao- tion. Of course, the two halves into which the plant thus divides itself are exactly like one another; and that gives us the basis for what we call HEREDITY— that is to say, the general similarity between parent and offspring. This similarity depends upon the fact that the two were once one, and when they spUt or divide each part continues to possess all the qualities of the original mass of which it once formed a portion. You will observe that I here use the words, parent and offspring. I do so, partly from custom, and partly to show where this reasoning leads U3.; But in reahty, in such very simple plants, neither part of the divided whole can claim to be either parent or child; they are equal and similar. In higher plants, however (as in higher animals), we find that the main portion of the plant continues to live and grow, and sends off smaller portions, known as spores or seeds, to reproduce its species. Here, we may fairly speak of the larger plant as the parent, and of the smaller ones which it de- taches from itself as its children or offspring. The truth is, every gradation exists in nature between these two extreme cases. The different types glide imperceptibly into one another. There is no one point at which we can definitely say, "Here reproduction by spHtting or division ceases, and reproduction by eggs, or by spores or seeds begins." Again, all the earlier and simpler plants are sexless ; they simply grow till they divide, and HOW PLANTS BEGAN TO BE. 26 then the two halves continue to exist inde- pendently. No two distinct plants or parts of plants are concerned in producing each new individual. But the higher plants, like the iiigher animals, are male and female. In sHch cases two distinct individuals combine to form a new one. They are its father and mother, so to speak, and the young one is their offspring. A httle gram of pollen produced by the male plant unites with a httle ovule or seedlet pro- duced by the female ; and from the union of the two springs a fresh young plant, deriving its peculiarities about equally from each of them How and why this great change in the mode of reproduction takes place is another of the questions we must discuss hereafter; I will only anticipate now the result of this discussion by saying briefly beforehand that plants gain in this way, because greater variety is secured in the offspring, and because the weak points of one parent are likely to be reinforced and made good by the other. Let us sum up our conclusions in this pre- hminary chapter :- - Plants are an older type of hfe than animals, ihey are the frst and most original form of living beings, and without them no Hfe of any sort wolild be possible. All hving matter is manufactured by plants out of material found floating in the air, under the influence of sun- light. How plants first came into existence we do not yet know ; but we may suspect that they grew, in very simple and small forms, at a V 26 THE STORY OP THE PLANTS. remote period, under conditions which now no longer exist. It is almost certain that the first plants were jelly-like specK3, floating freely in water. They must have been green, and must also have possesserl the essential plant-power of building up fresh living material when sunlight fell upon them. This power implies the other power of reproduction, that is to say of splitting up into two or more similar parts, each of which continues to live and grow like the original body. From such simple and very primordial plants all other and higher forms are most likely descended. I CHAPTER III. HOW PLANTS CAME TO DIFFER FROM ONE ANOTHER. All plants are not now alike. Some are trees, some herbs ; some are roses, some buttercups. Yet we have a certain amount of reason to believe that they are all descended from one and the same original ancestor ; and we shall see by and by that we can often trace the various stages in their long development. They differ immensely. Some of them are more advanced and more complex than their neighbours ; some are small and low, while others are tall and strong; some, like nettles and grasses, have simple and inconspicuous flowers, while others, like Ulies and orchids, have beautiful and very complicated blossoms, highly arranged in such ways as to attract and entice particular insects to visit and fertilise them. Again, some have HOW PLANTS CAME TO DIFFER. 27 tiny dry fruits, with small round seeds, which fall on the ground unheeded ; while others have brilliant red or yellow berries, or winged or feathery seeds, especially fitted for special modes of dispersion- In short, there are plants which seem, as it were, very low and uncivilised, while there are others which display, so to speak, all the latest modern inventions and improvements. The question is, How did they thus come to differ from one another ? What made them vary in such diverse ways from the primitive pattern ? In order to understand the answer which modern science gives to this question, we must first glance briefly at certain early sieps in the history of the process which we call creation or evolution. The earliest plants, we saw, were in all pro- bability mere tiny green jelly-specks, floating free in water, and taking from it small quantities of dissolved carbonic acid, which they manu- factured for themselves lato green living material when sunlight fell upon them. Now we shall have to consider another peculiarity of plants (and of animals as well) before we can thoroughly understand the first stage in the upward process which leads at last to the pine and the hly, the palm and the apple. Plants are made up of separate parts or elementii, known as cells, each of which consists of a thin cell-wall, usually containing Hving material. The very simplest and earliest plants, however, consist of a single such cell apiece; f" 28 THE STORY OF THE PLANTS i Aey are specks of green jelly, enclosed by a cell-wall, alone and isolated. In such cases, when the cell grows big and divides in two, each half floats off as a separate cell, or a separate plant, and continues to divide again and again, as long as it can get a suflicient amount of carbonic acid and sunlight. But in some instances it happens that the new cells, when budded out from the old ones, do not float off in water, but remain hanging together in long strings or threads, in single file, as you may see in certain simple forms of hair-hke pond-weeds. These weeds consist of rows of cells, stuck one after another, not unlike rows of pearls in a necklace. Of course the individual cells are too small to see with one's unaided eye ; but under a microscope you can see them, joined end to end, so as to form a sort of thread or long line of plant-cells. This " the beginning of the formation of the high - plants, which consist, indeed, of collections uf cells, arranged either in rows or in flattened blades, or many deep together in complicated order. However, the higher plants differ from the lower ones in something more than the number and complexity of the cells v/hich compose them. They are very varied ; and their vaiiety adapts them to their special circumstances. For example, desert plants, like the cactuses, have thick and fleshy leaves (or, rather, jointed stems) to itore up water, with a very tough skin to prevent evaporation. The flowers of each country, again, are exactly ad: ' d to the insects of that country ; and so are the fruits !j HOW PLANTfl CAMS TO DIFFER. 29 to the birds that swallow and disperse them. Howd'"^ this all come about? What made the adaptr «' ' ? It is a result of two great under- lying ^i mciples known as The Struggle for Lije^ and Natural Selection. Since each early plant goes on growing and dividing, again and again, as fast as it can, it must follow in time that a great number of plants will soon be produced, each fighting with the others for air and sunlight. Now, some of them must, by pure accident of situation, get better placed than others; and these will pro- duce greater numbers of descendants. Again, unless all of them remained utterly uninfluenced by circumstances (which is not likely) it must necessarily happen that slight differences will come to exist between them. These differences of outline, or shape, or cell-wall, may happen to make it easier or harder for the plant to get access tc carbonic acid and sunlight, or to disperse its young, or to fix itself favourably. Those plants, therefore, which happened to vary in the right directions would most easily go on living and produce most descendants, while those which happened to vary in the wrong directions would soonest die out and leave fewest descendants. Well, the world around us, both of plants and animals, is full of creatures all struggling against one another, and all competing for food and air and sunshine. Moreover, each individual pro- d:ices (as a rule) a vast number of young ; some- times, like the poppy, many thousand seeds on a single flower- stem. Now suppose only ten of 2IU THE STORY OP THE PLANTS. those seeds succeed in growing each year. In the first year, that poppy will have produced ten new poppy piants; the year after, each of those ten will have produced ten more, making the total 100; in the third year, they will bo 1,000; in the fourth, 10,000; and so on in the same progression till in a very few years the whole world would simply be full of poppies. And similarly with animals. If every egg in a cod's roe developed into a mature fish, the sea would soon be one sohd and compact mass of cod-fish. Why doesn't this happen? Because every other kind is producing seeds or eggs at about the same rate, and every one of them is fighting against the other for its share of light and food and soil and water. The stronger o^- better- adapted survive, while the weaker or less- adapted go to the wall, and are starved out of existence. Ac first, to be sure, it sounds odd to tallc of a Struggle for Life among plants, which seem too fixed and inert to battle against one another. But they do battle for all that. Each root is striving with all its might to fix itself underground in the best position ; each leaf and stem is atruggling hard to overtop its neighbour, and secure its fair share of carbon and of sun- shine. When a garden is abandoned, you can very soon see the result of this struggle ; for the flowers, which we only keep alive by weeding that is to say, by uprooting the sturdier com- petitors—are soon overgrown and killed out by the weeds— that is to say, by the stronger and better-adapted native plants of the district. This, then, is the nature and meaning of these HOW PLANTS CAME TO DIFFER. 31 I two great principles. The Struggle for Life meand that more creatures are produced than there is room in the world for. Natural Selec- tion (or Survival of the Fittest) means that among them all, those which happen to bo best adapted to their particular circumstances oftenest suc- ceed and leave most offspring. By the action of the two great principles in question (which affect all life, animal or vege- table) the world has been gradually filled with an immense variety of wonderful and beautiful creatures, all ultimately descended (as modern thinkers hold) from the selfsame ancestors. The simple little green jelly-speck, which is the primitive plant, has given rise in time to the sea-weeds and liverworts, then to the mosses and ferns, then to the simplest flowering plants, thence to the shrubs and trees, and finally to all the immense wealth and variety of fruits, flowers, and foliage we now see around us. The rest of this book will consist mainly of an exposition of the results brought about among plants by Variation, the Struggle for Life, and Survival of the Fittest. But before we go on to examine them in detail, I shall give just a few characteristic instances which show the mode of action of these important principles. There is a pretty wild flower in our hedges called a red campion, or " Eobin Hood." Now, a single red campion produces in a year three thousand seeds. But there are not three thou- sand times as many red campions this year as last, nor will there be three thousand times as 83 THB STORY OF THB PLANTS. many rr^re again next season. Indeed, if an annual plant had only two seeds, each of which lived and produced two more, and so on con- tmualiy, m twenty years its descendants would amount to no less than a million. From all this It necessarily results that a Struprrle for Exis- tence must take place among plants ; they fiffht with one another for the soil, the rain, the carbon, the sunshine. Again, take such a wild flower as th^'s very red campion. Why has it light pink petals? The reason is, to attract the insects which fertilise It. Flowers, m which the pollen is carried by the wind, never have brilliant or conspicuous blossoms ; but flowers which are fertiUsed by insects have almost always coloured petals to tell the insects where to find the honey. How did this come about? In this way, I imagine : Many plants produce a sweet juice on their leaves— for example, the common laurel. This juice, which IS probably of no particular use fco them, is very greedily eaten by insects. Now suppose some flower, by accident at first, happened to produce such sweet juice near its stamens, which (as we saw) are the organs for making pollen, and also near its pistil, which contains its young seeds or ovules. Then insects would naturally visit it to eat this sweet juice, which we commonly call honey. In eating it, they would dust themselves over with the floury pollen, by pure accident, and they would carry some of it away with them on their heads and legs to the next flower they visited. Chance would make them often rub ofi" the pollen and fertilise the flower ; and as such HOW PLANTS OAMB TO DlFFBB. $8 seedlings the vnnni ^ ^ ^"^^ vigoroufi the besf chanoeT^ouHrhinra^d' "°"'^ ^"'^^ the Struggle for ExSe «Thus ThTZ^ '" which made mnaf v,^ ., ^"® nowers visited and crossed - ?^ ^"^^^^ ^ """""^^ become ve'ry^n^etu:. Aga ^'iMhfv T" poned to havn hi-l^»,t i e"'"' " 'hey hai)- they would be mosf r.„ iT"^""'"" ">« ^oney, oftenest visited So T. ll ^'=<=""'i"'''eur^^ " """ '''"'^ ^hite? dusk; a red or n^nl hi '^''" '° "«" '° 'he almost inyrsibTe.'^'torrverthT"''l-.''''" "" pion is heavilv «^»„i ? ' *he white cam- night-flowerinrb S;'like%f "?^' *•" ""'^^ 'uherose. the^4=s;'trtbrSn^« 8 a4 THE 8TORT OF TBK TLANTi. i Observe the numerous points of similarity : all those ore white ; all are sweet-scented ; vAl are moth-fertilised. Why is this? Because the scent helps to show the moth the way to the flower when there is hardly enough light for him to see the white petals Thus every plant is adapted to its particular station in life, and its adaptation is the result of the Struggle for Existence, and Survival of the Fittest. Briefly put, whatever variation helps the plant in any way in any particular place, or at any particular time, is Ukely to give it an extra chance in the fight, and is therefore reproduced in all its descendants. So that is how plants began to vary. To sum up. Plants grow, because they keep on continually taking in carbon and hydrogen from the world outside them, under the in- fluence of sunlight. They multiply, because when they have attained a certain size they split up ^o form two or more individuals. They struggle *or life with one another, because more are produced than can find means of livelihood. And the struggle results in Survival of the Fittest. Or, looked at in another light. Plants multiply, and as they multiply by division the new ones on the whole resemble their parents ; this is the law of Heredity. But they do not exactly resemble them in every detail ; this is the law of Variation. And as some variations are to the good, and some to the bad, the better survive and produce young like themselves oftener than the worse do; this is the law of Naturhl Selection, CHAPTER IV. HOW PLANTS BAT. Wb saw in the last chaptei how and why plants came to differ from one another, but not why thev camj to be divided into well-marked groups or kmds, such as primroses, daisies, cabbaees. oaks, and willows. In the world around us we observe a great many different sorts of plants, not all mixed up together, so to speak, nor merging into ono another by endless gradations, but often cleany marked off by definite lines into groups or families. Thus a primrose is quite distinct from a crocus, and an oak from a maple *or the present, however, I do not propose to go into the question of how they came to be divided into such natural groups. I will berrin by tellinc you briofly how plants eat and drink, marry and rear famihes, and then will return later on to this problem of the Origin oj Species, as it is csalled, and the pedigrees and relationships of the leading plant families. Ji^at, And in this inquiry I will neglect for the most p^rt the very early and simple plants we have already spoken about, and wiU chiefly aeal with those more advanced and complicated types, the flowering plants, with which averv- body 18 familiar. ^ Plants Eat with their Leaves. The leaves are. in fact, their mouths and stomachs. 86 PTOUY OF TUB I'LANTl. Now, what is a loaf? It is usually a rnthor thin, flat body, often with two parts, a stalk and a blado, as in the oak or the beech ; though •ometimcs the stalk is suppressed, as in grass and the teasel. AlinoHt always, however, the leaf is green : it is broad and flat, with a large eipanded surface, and this surface is spread out horizontally, so as to catch as much as possible of the sunlight that falls upon it. Its business is to swallow carbonic acid from the air, and digest and assimilate it under the influence of sunlight. And as different situations require different treatment, various plants have leaves of very different shapro, each adapted to the habits and manners c. the particular kind that produces them. The difference has been brought about by Natural Selection. What does the leaf eat? Carbonic acid. There ib a small quantity of this gas always floating about dispersed in the air, and plants fight with one anotner to get as much as possible of it. Most people ima^ne plants grow c'^t of the soil. This is quite a mistake. The portion of its solid material which a plant gf^ts out of the soil (thoupu absolutely necessary to it) is hardly wortn taking into consideraiion, nume- rically speaking; by far the larger part of its substance comes directly out c^ the air as carbon, or out of the water as hydrogen and oxygen. You can easily see that this' h so if you dry a small bush thoroughly, leaves and all, and then burn it. What becomes of it in such circumstances? You will find thf*. the greater part of it disappoars, or goes otf BOW PLANTB lAT. 87 Into the fttraoflphore; the carbon, nnlting with oxygon, goes off in the form of carbonic acid while the nydrogen, unifing with oxygen, goes off in the form of steam or vapour of water. What is there left? A very small quantity of solid matter, which we know as ash. Well, that ash which returns to the soil in the solid condition' IS practically almost the only part the plant got from the soil ; the rest returns as gas and vapour to the air and water, from which the plant took them. You must never forget this most im- portant fact, th&t plants grow mainly from air and water, and hardly at all from the soil beneath them. Unless you keep it firmly in mind, vou will not understand a great deal that follows. Why, then, do gardeners aad farmers think so much about the soil and so little about the air, which is the chief source of all living material ? We fihall answer that question in the next chaptor, when we come to consider What Plants Drink, and ^,hat food they take up dissolved in their water. Carbonic acid, though itself a gas, is the cliief source of the solid material of plants. Hov; do plants eat it ? By means of the green loaves, which suck in fleeting particles of the gaseous tood. Their eating lo thus more like breathing than ours : nevertheless, it is true feeding : it is their way of taking in fresh material for building up their bodies. If you examine a thin slice trom a leaf under the microscope, you will find that Its upper surface consists of a layer of cells THE STORY OF THE PLANTS. with transparent walls, and no colouring matter (Fig. 1). These cells are full of water; they form a sort of water- cushion on the top of the leaf, which drinks in carbjnic acid (or, to be quite correct, its floating form, carbon dioxide) from the air about it. Immediately below this cushion of water-cells you come again upon a QQaaoapgrDar *\C3CDCpO\pCDC3ClOn}C}Q FIG. 1.— A THIN SLICE FROM A LEAF, SEEN UNDER THE MICROSCOPE. On top Ere water-cells, which suck in carbonic acid. Beneath these are green cells, which assimilate it under the influence of sunlight. The sijongy lower portion is used for evaporation. firm layer of closely-packed green cells, filled with living green-stuff, which take the carbonic acid in turn from the water-cells, and manufacture it forthwith into sugars, starches, and other materials of living bodies. The lowest spongy part evaporates unnecessary water, and so helps to keep up circulation. HOW PLANTS EAT. S9 The plant has often many hundred leaves, that is to say, many hundred mouths and stomachs. Why do plants need so many when we have but one? Because they cannot move, and because their food is a gas, diffused in minute quantities through all the atmosphere. They have to suck it in wherever they can find it. And what do they do with the carbonic acid when :>nce they have got ^^ ? Well, to answer that question, I must tell you a httle more about what the ordinary greon leaf is made of, and especially about the green-stuff in its central cells. ^ Now what is this green-stuff? It is the true life-material of the plant, the origin of all the hving matter in nature. You and I, as well as the plants themselves, are entirely built up of hving jelly which this green-stuff has manufactured under the influence of sunlight. And the mate- rial that does this is such an important thing in the history of Hfe that I will venture to trouble you with its scientific name. Chlorophyll. When sunlight falls upon the Chlorophyll or gieen-stuff in a living leaf, in the presence of carbonic acid and water, the chlorophyll (or, to be quite accurate, the living matter or protoplasm with chlorophyll embedded in it) at once proceeds to set free the oxygen (which it turns loose uoon the^ air again), and to build up the carbon and hydrogen (with a little oxygen) by various stages into a material called starch. This starch, as you know, possesses energy— that is to say, latent light and dormant heat and movement, because we can eat it and burn it within our bodies. Other materials, hydro-carbons and carbo-hy- drates, as they are called, are made in the same 40 THE STORY OP THE PLANTS. I* ! ' I way. The main use of leaves, then, is to eat carbon and drink water, and, under the influ- ence of sunlight, to take in energy and build them up ip^o living material. The 8ta»'ch and sugar and other things thus made are afterwards dissolved in the sap, and used by the plant to manufacture new cells and leaves, or to combine with other important mate- rials of which I shall speak hereafter, in order to form fresh living chlorophyll, or rather proto- plasm with chlorophyll in it. Now we know what leaves are for ; and you can easily see, therefore, that they are by far the most essential and imports it part of the entire plant. Most plants, in fact, consist of Uttle else than colonies of leaves, together with the flowers which are their reproductive organs. We have next to see What Shapes various Leaves assume, and what are their reasons for doing so. The leaf has, as a rule, to be broad and flat, in order to cat^h as much carbon as possible ; it has also usually to be expanded horizontally to the sunhght, so as to catch and fix it. For this reason, most leaves that can raise themselves freely to the sun and air are flat and horizontal. But in very crowded and overgrown spots, like thickets and hedgerows, the leaves have to fight hard with one another for air and sunlight ; and in such places particular kinds of plants have been developed, with leaves of special forms adapted to the situation. The fittest have survived, and have assumed such shapes as natural selection dictated. Where the plants are large and grow freely upward, with plenty of room, the leaves are HOW PLANTS BAT. 41 usually broad and expanded, as in the tobacco- plant and the sunflower. Where the plants grow thick and close in meadows, the leaves are mostly long and narrow, like grasses. In overgrown clumps and hedgerows they are generally much subdivided into numerous little leaflets, as is the case with most ferns, and also with herb-Eobert, chervil, milfoil, and vetches. In these last cases, the plant wants to get as much of the floating carbonic acid, and of the flunhght, as it can ; and therefore it makes its leaves into a sort of divided network, so as to entrap the smallest passing atom of carbon, and to intercept such stray rays of broken sunlight as have not been caught by the taller plants above it. In almost all oases, too, the leaves on the same plant are so arranged round the stem and on the branches as to interfere with one another as httle as possible ; they are placed in an order which allows the sunshine to reach every leaf, and which secures a free passage of air between them. An interesting example of the way some of these principles work out in practice is afforded us by a common httle English pond-weed, the water-crowfoot. This curious plant grows in streams and lakes, and has two quite different t^es of leaves, one floating, and one submerged. The floating leaves nave plenty of room to develop themselves freely on the surface of the pond; they loll on the top, well supported by the mass of water beneath; and, as there is httle compe- tition, they can get an almost unhmited supply of carbonic acid and sunshine. Therefore, they 42 THKi STORY OP THE PLANTS. II ue larga and roundish, like a very full ivy-leaf. But the submerged leaves wave up and down ia hhe water below, and have to catch what little dissolved carbonic acid they can find in the pond around them. Therefore they are dissected into endless hair-like ends, which move freely about in the moving water in search of food-stuff. The two types may be aptly compared to lungs and gills, only in the one case it is carbonic acid and in the other case oxygen, that the highly-dissected organs are seeking in the water. As a general rule, when a plant can spread its leaves freely about through unoccupied air, with plenty of sunlight, it makes them circular, or nearly so^ and supports them by means of a stem in the middle. This is particularly the case with floating river-plants, such as the water-lily and the water-gentian. But even terrestrial plants, Fvhen they can raise their foliage easily into unoccupied space, free from competition, have similar round leaves, supported by a central leaf-stalk, as is the case with the familiar garden annual popularly (though erroneously) known as nasturtium. (Its real name is Tropceolum.) On the other hand, when a plant has to struggle hard for carbon and sunlight in overgrown thickets, or under the water, it has usually very much subdivided leaves, minutely cut, again and again, into endless segments. Submerged let-ves invariably display this tendency. But that does not conclude the whole set of circumstances which govern the forms and size of leaves. Not only do they want to eat, and to HOW PLANTS BAT. 48 have access to sunshine; they must also be sup- ported or held in place so as to catch it. For this purpose they have need o.* what we mav venture to describe as foliar architecture. This Sf ? -^^^ u^l ^""'"^ ^^ "bs or beams of harder material, which ramify through and raise aloft the softer and actively living ceU-stuff. They are, as it were, the skeleton or framework of the leaf; and in what are commonlv known as -skeleton leaves " the living cell-stuff between has been rotted away, so as to display this harder underlying skeleton or framework. ^ It is con^- posed of specially hardened, lengthened and strengthened cells, and is int^ndel, not o^^Y to do certain hving work in the plant (as we shall see hereafter) but also to form a supportini scaffoldmg The material of which ribs o? beams are composed is called "vascular tissue" --a not very well chosen name, as this material has only a slight analogy to what is called the vascular system (or network of blood-vessels) in skZnn ^'S- ^ -1 ^1* '^ T""^ ^^^^ lik« the bony n.nnl ..^'^'^^y^Y' t^e ribs thomselvcs are usually called veins-a very bad name again, as they are much more like the bones of a wing or hand ; they are mainly there for support, a! a bony or wooden framework, though they also act for the conveyance of sap or water. And now we are in a position to begin to understand the various shapes of leaves as we urfon Tf •'' '?''?''; .^^'' ^^P^"^ "^ost of all vSno f'^ inherited types of ribs or so-called veins, and these types are usually pretty constant 44 THE TTORY OP THR PLANTS. il ; \ \l I in great groups of plants closely related by descent to one another. The immense difference in their external shape (which often varies enor- mously even on the same stem) is mainly due to thp relative extent to which the framework is fii.ed out or not with Hving cell-stufif, or, as it is technically called, cellular tissue. There are two chief ways of arranging the ribs or veins in a leaf, which may be distinguished as the filiger-like and the feather-like methods (in riG. 2.— FiNOER-VEiNED LEAVES. The velns are the same in the three leaves, but they differ in the amount to which they are flUed in. technical language, palmate and pinnate). In the finger -like plan the ribs all diverge from a common point, more or less radially. In the feather -like plan the ribs are arranged in oppo- site pairs along the sides of a common line or midrib.^ Yet even these two distinct plans merge into one another by imperceptible de- grees, as you can see if you look at the accom- panying diagram. Now let us take first the finger-veined type (Fig. 2). Here, if all the interstices of the ribs are fully filled out with cellular tissue, we get a HOW PLANTS EAT. 45 roundish lea ike that of the so-called nastur- tiura. But if the ribs project a little at the edge -n other words, .(the cellular tissue does not quite fill out the whole space between them- we get a slightly indented leaf, like that of the scarlet geranium or the common mallow. If the untilled spaces between the ends of the ribs are much greater, then the ribs project into marked pomts or lobes, and we get a leaf like that of ivy Fio. S.-PEATHER-vEiNED LEAVES. The four leavcs have similar veins, but are differently filled ir. Carry the starving of the cellular tissue a little further still, and we have a deeply-indented leaf iike that of the castor-oil plant. Finally, let the spaces unfilled go right down to the common centre from which the ribs radiate, and we get a divided or compound leaf, like that of the horse- chestnut, with three, five, or seven separate leaflets. (See Fig. 5, No. i.) Similarly with the feather -veined type (Fig 3)- the spaces between the ribs may be more or less niled with cellular tissue in any degree you 46 THR BTCUY OP THR PL ANTS. choose to mention. When they are very fully filled out, you get a leaf like that of bladder > tA V • -' > to aj Ji I senna. A little more pointed, and less filled out at the tips, it becomes like argel. When HOW PLANTS BAT. 47 tho edge IS not quito liUod out, but irrocularlv mdented, we get forum like the oak leaf, iinally, when tho uulentations go to the very bottom of each vein, so as to reach the midrib we get a compound loaf hke that of the vetch' wiUi a number of opposite and distinct leaflets. ' The reason why some leaves are thus more hlled out than others is simply this : it depends upon .he freedom of their access to air and sunlight. I do not mean the freedom of access of the particular leaf or tho particular plant, but tho average ancestral free- dom of access in the kind they belong to. Each kind has adapted itself, as a rule, to certain situa- tions for \\,iich it has special advantages, and it has learnt by the teach- ing of natural selection to produce such leaver as best fit its chosen site and habits. Where access to carbon and sunlight IS easy, plants usually produce very full round leaves, with all the interstices between the ribs tilled amply in with cellular tissue ; but where access is difficult, they usually produce ra%er starved and unfilled leaves, which consist, as it Z^^%u- f^^^^^y covered skeletons (Figs. 4 and pj. ihis last condition is particularly observable in submerged leaves, and in those which grow m very crowded situations. liQ. 6.— I. Parallel veins, as seen in one great group of plants, the lilies. II. Branching veins, as seen in another great group, the trees and herbs of the usual type. v^ 48 THE STORY OF THB PLANTS. The two types of rib-arrangement to which 1 have already called attention exist for the most part in one of the two great groups of flowering plants about which I shall have more to Huy to you hereafter. There is yet a third type, how- ever, which occurs in the other great group (that of the grasses and lilies), and it is known as tha parallel (Fig. 6). In this typo, the ribs do not form a radiating network at all, but run straight, or nearly so, through the leaves. Examples of it occur in almost all grasses, and in tulips, daffodils, lily of the valley, and narcissus. Leaves of this sort have seldom any leaf-stalk; they usually rise straight out of the ground, more or less ereot, and their architectural plan is gene- rally quite simple. They are seldom toothed, and hardly over divided into deeply-cut segments or separate leaflets. A few more peculiarities in the shapes of leaves must still be noted, and a few words uced in describing them must be explained very briefly. When the leaf consists all of one piece, no matter how much cut up and indented ut the edge, it is said to be "simple"; but if it is divided into distinct leaflets (as in Fig. 5), it is called "compound." If the edge is unindented all round (as in Fig. 6), wc say the leaf is "en- tire " ; if the ribs form small projections at the edge (as in Fig. 4), we call it " toothed " ; if the divisions are deeper, we say it is " lobed " ; and when the lobes are veiy deeply cut indeed, we call it " dissected." Thus, in order to describe accurately the shape of a leaf, we need only say which way it is veined or ribbed— whether finger- a a ^ now PLANTS BAT, i9 wise, feather-wiBe, or with parallel veint-Md how much, if at »U, it is out or divided, .nf " -.'if i'*"^''"'', however, occur, in accord- kind have been devofoped to inhabit, ^n tuT'^ P'""!'' '°'" ''''""P'«' 'ho leaveB are usua ly opposite, bo as to clutch more readUy Bhl d"^*"?? "1"°"' "'^'^y^ ™°^« °' l^^" heart-' brionv Th«^ "' "? i" «°»volvulu8 and black hln^^; ^ ! H'"'''^ ?^ ^°''«*' "•««8. 0° 'he other hand, tend to be what is known as ovale in shape, like the beech and the poplar • while tha^«°^"'.' ^r' "" " ""'« ""^-^'-^^-J. in order n At '^"L'^^y °°' overshadow and rob its neighbour. This one-sidedness is even more markedly seen in th, hot-house begoniL SoZ leaves, again, are minutely subdivided into leaflets twice or three times over ; such leaves f/vo,?! °. ^^ ^"J"y \ '''^^y com'pound. Bu s ^"hI f ^P^1'' "' ^^^y erow (and this book IS written m the hope that it may induce you So do so), you will generally be able to see that the Shapes and peculiarities of leaves have some and their habits and mannerB. ' I have spoken so far mtanly of quite oertral and typicalleaves, which are arranged with a single view to the need for feeding. But plants are exposed to many dangers :n We besides the danger of starvation, and they guard in various wajrs against all these dan/ers. On? ve^ bvTaL°r •? *^' '^''^g^^ of^eing de'vou^l^ by grazing ammals, and, to protect themselves 50 THB 8T0RT OF THE PtiAlfT«. I| i- = ■! I ^Ji aRainflt It, many plants produce loaves which are prickly, or fltinginK, or otherwise unpleasant. The common holly is a familiar instance. In this case ihe rihs are prolonged into stiff and prickly points, which wound the tender noses of donkeys or cattle. We can easily see how such a protection could be acquired by the holly-bush through the action of Variation and Natural Soloction. For holly grows chiotly in rough and wild spots, where all the green leaves are liable to be eaten by herbivorous animals. If, therefore, any plant showed the slightest tendency towards pricklinoss or thominess, it world be more likely to survive than its un- protected neighbours. And indeed, as a matter of fact, you will soon see that almost all the bushes and shrubs which frequent commons, such as gorse, butcher's broom, hawthorn, blackthorn, and heather, are more or less spi .y, though in most of these cases it is the branches, not the leaves, that form the defensive element. Holly, however, wastes no unnecessary material on defensive spikes ; for though the lower leaves, within reach of the cattle and donkeys, are very \)rickly indeed, you will find, if you look, that Ihe upper ones, above six or eight feet from the ground, are smooth-edged and harmless. These upper leaves stand in no practical danger of being eaten, and the holly therefore takes care to throw away no valuable material in protecting them from a wholly imaginary assailant. Often, too, in these prickly plants we can trace some memorial of their earlier history. Gorse, for example, is a peaflower by family, !^ 1 1 HOW PLANTS BAT. 01 the pea the bean, the lafiurnum. the clover «„1 uZ:^"'lT'''' ".«««. Bhrub; and oUmC •et of tref '-leaved peallowors, like the cfovera and lucerne, : but, owing «, its ohoson home „" open uplands, almost all its upper leaveg have ^Z ':nt^T'^ 'or P„ :K>.e.Tf doTenco into !n iT" ''P'"°-'''^« pricklv,. Indeed, the leave, and tb^l ^"''**' '■'"' "" olover-like anoestorg; ^osenf^S '''^'' "^ '^'"°'" exactly similar to those of the common penisla so muol, cultivated n hot-houge,i. As tU plant grows, however the trefoil leaves (jraduafiy give vh-B t^Tl^ tpt:rZ If W '•'-V"'u- to pri'cwf ^e ?u«t fil.1 ^ .^'^^".go^e-leavfis. Hence vie Trsi « 1 ° ''"''?^°8 "^»' ">e ancestors of fn^ .iTf ^ ".""^ genistas, bearing trefoil leaves • selection If'' '>,T8'' *e """on o naturli se ection, the prickliest among them survived till they acquired their existing £p?ny foulee K?w ni r '"r^^'^J^^cestois, and only as they oTa^to'ris'tr" ''"' ''''' *"^ °-« ^P-i'^ oriiwTT/ ^"'' *"^^ °°« ^°^d about the ongm of leaves m general. Very runule olanta we saw, consist of a single ce^ whi^h tToi THE STORY OP THE PLANTS. meroly a leaf, but also at the same time a flower, a seed, a root, a branch, and everything. In other words, in very simple plants a single cell does rather badly evftrything which in more advanced and developed plants is better done by distinct and highly-adapted organs. The whol' evolution of plants consists, in fact, in the tellin j off of particular parts to do better what the primitive cell did for itself but badly. Above the very simple plants which consist of a single cell come other plants, which consist of many cells placed end on er d together, as in the case of the hair-like water-weeds ; and above these agam come other and rather higher plants, in which the cellular tissuo assumes the form of a flat and leaf-like blade, as in many broad sea- weeds. None of these, however, are called leaves in the strict se ^e, because they consist of cells alone, withoi any ribs or supporting framework. The higher types, however, like ferns and ilowering plants, have such ribs or frameworks, made of that stiffer and tougher material called vascular tissue. >- This is the most general distinction that exists between plants ; the higher ones are known as Vascular Plarts, including all those with true leaves, such as the common trees, herbs, and shrubs, and the ferns and grasses — in fact, almost all the things ever thought of as plants by most ordinary observers ; the lower ones are known as Cellular Plants, and include the kinds without true leaves or vascular tissue, such as the seaweeds, fungi, r«nd microscopic plants only recognised as a rule by botanical students. 1 I HOW FLANTB BAT. 68 The higher plants, then, have for the most part special organs, the leaves, told off to d' work for them as mouths and stomachs • whUe other organs are told off to do other special work of their own-as the roots to drink, the flowers 1»/T*t"''' '^? ^'^°" ''"^ ''^^' to carry on the life of the species to other generations and so for h, down to the hairs that protect the surile or the glands that produce honey to attrlcVthe fertihsmg msects. To the end, however all cfc tcid 'if''""' ■■''"" **•« po;err:aTc:" niTnta t ' °«<=«8sary ; so that many higher plants have no true leaves, but use portions of Any part of the plant which contains the active living green-stuff, or chlorophyll, can r,erfom the functions of a leaf. In vefy d^y or' deseS fcnd''"^'' r^^""' "««'^««' because the r flat and exposed blades would allow the water aesert plants, hke the cactuses, and many kinds a all'"1n'.r^ euphorbias, have no true W at all , in their place they have thick and fleshv jo Ltd 'Thi:P 'r'-"^' '" «h^P«' ^""J "^"o-ll^ jomtea. ihese stems are covered with a fhiVl/ mnsp^ent skin or epidermis, tole^sre^poS: hah^; Z "" P'^otected by numerous stinging aftlt /P'?^'', ^''^'"^ ^'^^ to keep ofl' thf a retervlrS''' . ^'T? u°' *'^ type^re u ed dnrin wi? ^ °! '^**®'"' ■^^'<=^ the plant sucks up t^ln^w ^ ^frequent rains ; ani aa they con? tain chlorophyll, like leaves, they serve b lust 64 THE BTOKY OF THE PLANTS. a . II Many other plants which live in dry or sandy places, like our common English stone-crops, do not go quite as far as the cactuses, but have thick and fleshy leaves on thick and fleshy stems, to prevent evaporation. As a general rule, in- deed, the drier the situation a plant habitually frequents the fleshier are its leaves, and the greater its tendency to make the stem share in the work of feeding, or even to get rid of foliage altogether. In Australia, however, most of the forest trees, Hke the eucalyptuses, have got over the same difficulty in a different way ; they arrange their leaves on the stem -» as to stand vertically to the sun's rays, instead of horizontally, which saves evaporation, and makes the woodland almost entirely shadeless. Many of these Aus- tralian trees, however, have no true leaves, but use in their place flattened green branches. Some plants are annuals, and some peren- nials. When annuals have flowered and set their seed they wither and die. But perennials go on for several seasons. Most of them, how- ever, in cold climates at least, shed their leaves on the approach of winter. But they do not lose all the valuable material stored up in them. Trees and shrubs withdraw the starchy matter mto a special layer of the bark, where it remains safe from the winter frosts, and is used up again in spring in forming the new foliage. This new foliage is usually provided for in the preceding season. If you look at a tree in late autumn, after the leaves have fallen, you will see that it IS covered by little knobs which we know as HOW PLAMIS EAT. 66 buds. These buds are the foliage of fche coming season. The outer part consists of several layers of dry brown scales, which serve as an overcoat to protect the tender young leaves within from the chilly weather. But the inner layeis consist of the deUcate young leaves them- selves, which are destined to sprout and grow as soon as spring comes round again. Even the scales, indeed, are very small leaves, with no living material in them ; they are sacrificed py the plant, as it were, in order to keep the truer leaves within snug and warm for the winter. Nor do the autumn leaves fall off by pure accident ; some time before they drop the tree arranges for their fall by making a special row of empty ceUs where the leaf-stalk joins the stem or branch ; and when frost comes on, the leaf separates quietly and naturally at that point as soon as the valuable starchy and Hvine material has been withdrawn and stored in the permanent layers of the bark for future service. bmaller and more succulent plants do not thus withdraw their living material into the bark m autumn ; but they attain much the same end in different manners. Thus lilies and onions store the surplus material they lay by during the summer at the base of their long leaves, and the swollen bases thus formed pro- duce what we call a bulb, which carries on the life of the plant to the next season. Other plants, like the common English orchids, store material m underground tubers; while others again, and by far the greater number, so store It in the root, which is sometimes thick and 66 THE STORY OF THE PLANTS. swollen, or in an underground stem or root- stock. In most oases, however, perennial plants take care to keep over their live material from one season to the other by some such me£.ns of permanent storage. They are, so to speak, capitalists. Natural selection has of tourse preserved those plants which thus laid by for the future, and has killed out the mere spendthrifts which were satisfied to live for the fleeting moment only. The soil of our meadows in winter is full of tubers, bulbs, and root- stocks ; while our shrubs and trees carry over their capital from season to season in their living bark, secure from injury. In one way or another iall our perennial plants manuge to tide their living green-stuff, or at least its raw material, by hook or by crook, over the dangers of winter. I have given so much space to the subject of leaves because, as you must see, the leaf is really the most important and essential part of the entire plant — the part for whose sake all the rest exists, and in which the main work of making living material out of hfeless carbonic acid and water is concentrated. Let us sum up briefly the main facts we have learned in this long chapter. Plants eat earbonic acid under the influence of sunlight. They store up the solar energy thus derived in starches and green-stuff in their own booties. Very simple plants, which float freely in water, eat and drink with all portions of their surface. But higher plants eat with i! HOW PLANTH DKINK. 67 Bpeoial organs. These organs are known as leaves and are the parts where the chief busi- ness of the plant is transacted. A leaf is an expanded mass of cells, containing living gre -i-stuff, supported on a tougher frame- work, or r.j-hke skeleton. Leaves take in car- bonic acid by means of tiny absorbing mouths, which exist on their upper surface ; and the; s^ii^ri'^u'* ^^ the oxygen, by the aid of sunlight building up the carbon into starch with hydrogen from the water supplied by the roots to them. Leaves are of different shapes. Dlanttli^' *^! work they have to do for the plant m different situations. Where carbon and sunlight abound they are round, or nearly so • where carbon and sunlight are scanty, or much competed for, they are more or less divided into minute sections. CHAPTER V. HOW PLANTS DKINK. We have now learnt that plants really eat for the most part with their leaves. They ^row on he whole, out of the air. not, ., : most people seem to fancy, out of the soil. Yet you must have noticed that farmers and gardeners think a ^eat deal about the ground in which they plant ^Z!l Tv, ""^"^^ru^' apparently, about the air abound them, What is the reason for this curious neglect of the real food of plants, and this curious importance attached to the mould or soil they root in ? Ih 68 THE STORY OP THE PLANTS. That is the question we shall have to consider in the present chapter ; and I shall answer it in part at once by saying beforehand that, though Elants do grow for t^'^ most part out of the car- onio acid supplied oy the air to the leaves, they also require certain things from the soil, less important in bulk, but extremely necessary for their growth and development. What they eat through their leaves is far the greatest in amount ; but what they drink through their roots is nevertheless indispensable for the pro- duction of that living green- stuff, protoplasm with chlorophyll, which, as we saw, is the original manufacturer and prime maker of all the material of life, either vegetable or animal. Plants have roots. These roots perform for them two or three separate functions. They fix the plant firmly in the soil ; they suck up the water which circulates in the sap ; and they also gather in solu'ion certain other materials which are necessary parts of the plant's living matter. The first and most obvious function of the root is to fix the plant firmly in the soil it grows in. Very early floating plants, of course, have no roots at all ; they take in water and the dissolved materials it ccr iains, with every part of their surface equally, just as they take in carbonic acid with every part of their surface equally. They are all root, all leaf, all flower, all fruit. But higher plants tend to produce different organs, which have become specially HOW PLANT" DRIHK. 69 adapted by natural selection for special purposes. If you BOW a poa or bean you will find at once that the young seedling begins from the very firs to distinguish carefully between two main parts of Its body. In one direction, it pushes downward, forming a tiny root, which insinuates Itself with care among the stones and soil; in the other direction, it pushes upward, forming a baby stem, which gradually clothes itself with leaves and flowers. The tip of the root is the part of the plant which exercises the greatest discrimination and ingenuity, so much so that Darwin likened it to the brain of animals. For it goes feeling its way underground, touching here, recoiling there, insinuating httle fingers among pebbles and crannies and trying its best by endless offshoots to lix the plant with perfect security. Large trees, m particular, need very firm roots, to moor them in their places, and withstand the force of the winds to which they are often subject. After every great storm, as we know, big oaks and pines may be seen uprooted by the power of this invisible but very dangerous enemy. The root, however, does not serve merely to anchor the plant to one spot, and secure it a tnZ '""t^v. '^ *^ ^^^T ^.^^ ^^^^ ' i* ^^90 drinks water The hairs and tips of the root absorb moisture from the soil ; and this water circulates freely as sap through the entire plant, dissolving and carrying with it the starches and othe! materials which each part requires for its growth and nourishment- (Figs. 7, 8, and 9). Without 60 THE STOBY OP THE PLANTS. water, as we all know, plants will wither and die ; and the roots push downward and outward in every direction in search of this necessary of life for the leaves and flowers. In addition to these two functions of fixing the plant and drinking water, however, roots per- form a third and almost more impor- tant one in absorbing the other needful materials ofjilant life from the soil about them. They drink, not water alone, but other things dis- solved in it. What are these other things ? Well, the answer to that question will fairly round off our first rough idea of the FI0.7. no. 8. no. 9. ^^^^ materials that Fig. 7. ROOT OF THE CARROT. ^^^ ^« "^^^^ ^P ^^9°^' Fig. 8. ROOT OF THE FROGBiT, We saw already that FLOATING IN WATER. Fig. 9. plants eat carbouand ROOT OP THE RADISH. The hydrogcu from the small hair-like ends drink in airanrl watpr- nnf of water and dissolved food-salts. fJ^^ ana water , out ot these they manufac- ture a large number of compounds, such as HOW PLANTS DRINK. 61 starches, oils, sugars, and so forth, all of which contain a little oxygen, but far less than the amount contained in the carbonic acid and water from which they are manufactured. These use- ful materials, however, though possessing energy, that IS to say the power of producing light and heat and motion, are not exactly live-stuffg • m order to make out of them the living green matter of leaves, chlorophyll, or the living cell- stuff of all bodies, animal or vegetable, proto- plasm, we must have a fourth element, nitrogen • and that element is supplied by the roots in solution. So now you see the fuU importance of the roots ; they add to the oils and starches manu- factured m the leaves that mysterious body nitrogen, which is necessary in order to turn these things into protoplasm and chlorophyll. A few other things besides nitrogen are also needed by the plant from the soil ; the most important of these are sulphur and phosphorus ihe plant, however, does not take in these substances in their free or simple form, as nitrogen, sulphur, and phosphorus, but in com- position, as soluble nitrates, sulphates, and phosphates. Now, I am not going to trouble you with a long chemical account of how the plant combines these various materials— a thing about which even chemists and botanists themselves know as vet but very little. It will be enough to say here that the plant builds them up at last into an extremely complex body, called protoplasm ; ea THE BTORl OF THE PLANTS. and this protoplasm is the ultimate living matter, the "physical basis of life;" the thing without which there could be no plants or animals possible. What is protoplasm— this mysterious stuflf, which builds up the bodies of plants and animals ? It is a curious transparent jelly-like substance, full of tiny microscopic grains, and composed of carbon, hydrogen, oxygen, nitrogen, and sulphur. Sometimes it is almost watery, sometimes half- horny, but as a rule it is waxy or soft in texture. It is very plastic. Its peculiar characteristic is that it is restlessly alive, so to speak ; seen under a microscope, it moves about uneasily, with a strange streaming motion, as if in search of something it wanted. It is, in point of fact, the building-material of life ; and out of it the living parts of every creature that lives, whether animal or vegetable, are framed and compounded. But it is plants alone that know how to make protoplasm, or other organic matter, direct from the dead material around them. Animals can only take living matter ready-made from plants, and burn it up again by reunion with oxygen in their own bodies. The plant manufactures it. The animal destroys it. Chlorophyll bodies or the active groen-stutf of loaves is a special modi- fication or variety of protoplasm ; and chlorophyll alone possesses the power to manufacture new energy.yielding and living material, under the mfluence of sunlight, from the dead and inert bodies around it. The materials which it thug produces are afterwards worked up by the plant, together with the nitrogen, sulphur, and phos- phorus supplied by the roots, into fresh starch and HOW PLANTS DRINK. 63 fresh protopIaHiii, containing fresh chlorophyll. These the animal may afterwards eat, either in the form of leaves like grass, or in the form of seeds or fruits, like com, rice, or bananas. The tinie'^t primitive one-colled plant con- tains protoplasm and ch!- -ophyll (though a few degenerate plants, like 'ungi, have none of the Hving green-stuff, and can make no new living material for themselves, but depend, like animals, upon the industry of others). Every living cell of every plant contains protoplasm ; a cell without any is dead and lifeless. Protoplasm, in short, is the only living material we know ; and its life constitutes the larger life of the wholes compounded of it. Well, now you are in a position to see why the farmer and the gardener attach so much importance tt the soil, and so little, apparently, to the air and the sunlight. The reason is that the air is everywhere ; you get it for nothing ; but the soil costs money, and, when cultivated, it requires to be supplied from time to time with fresh stores of the particular materials the plants take from it. Let me give two simple parallel cases. A fire is made by the combination of two sorts of fuel— coal and oxygen. One is just as necessary for fire-making as the other. But we buy coal dear, and we neglect to take oxygen into consideration accordingly. The reason is that oxygen exists in ab. ndance everywhere ; so we don't have to buy it. If we paid a pound a ton for it, as we do with coal, we should very soon remember 64 THE 8T0BT 0» THW PLANTS. ifi ¥ II s how necessary a part it is of evory fire. Even at present we are obliged to provide for its free admission by the bars of the grate, and by checking or roguhiting its ingress we can slacken or quicken the burning of the fire. Or, to takt3 another analogy, oxygen is just as necessary to human beings and other animals as food and drink are. But, as a rule, wo get oxygen everywhere in such great abundance that we never think of taking it into practical consideration. Still, in the Black Hole of Cal- cutta, the unhappy prisoners thoroughly realised fche full value of oxygon, and would gladly have paid its weight in gold for the life-giving element. Now, carbonic acid, on which plants mainly live, is not so common or so abundant a gas as oxygen ; but still, it exists in consideraole quantities in the air everywhere. So most plants ire able to get almost as much as they need of it. Nevertheless, submerged plants, and plants that grow in very crowded places, seem to com- pete hard with one another for this aerial food ; and in certain cases they appear to live, as it were, in a very Black Hole of Calcutta, so far as regards the supply of this necessary material. In farms and gardens, however, the f'^.rmer takes care that every plant shall have plenty of room and space^n other words, free access to sun- light and carbonic acid. He " gives the plants air," as he says, not knowing that he is really supplying them with their aerial food- stuff. He does this by keeping down weeds — by ploughing, by digging, by hoeing, or tilling. Indeed, what .1 HOW PLANTS DRINK. re i^ My mean by cultivation? Nothing than destroy ing the native vegetation of a do we more ^ ^^ place, in order to' make room for other plants that we desire to multiply We plough out the grasses and herbs that occupy the soil ; we sow or plant thinly seeds or cuttings of corn or vinos or potatoes that we desire to propagate. We give these new plants plenty of space and air- in other words, free access to sunlight and car- Ionic acid. And that is the fundamental basis of cultivation — to keep down certain natural plants of the place, in order to give free room to others. But as the orop-plants require to root them- selves, the farmer naturally thinks most of the soil they root in— which he has to buy or rent, while the carbonic acid comes froely to him, unperceived, with the breath of hoaven. Where water is scarce, as in irrigated dosert lands, the farmer recognises quite equally t>e importance of water. But he never recognises ihe true importtnce of carbonic acid. That is why most people wrongly imagine that plants grow out of the soil, not out of the air.' Still, when we burn them, the truth becomes clear. The portion of the plants derived from air and water goes off again into the air in the act of burning : so too does the nitrogen : the remaining portion derived direct from the soil is only the insignificant resi- due returned to the soil as ash when we bum the plant up. Nevertheless, the farmer often needs to supply certain raw materials to the soil for the plants 6 »! 66 THE 8T0BY OF THE PLANTS. he cultivates. These raw materials are called manures ; they are mostly rich in nitrates and phosphates; and as they are usually the only things directly supplied to plants by human agency — the carbonic acid and water being supplied by wind and rain in the ordinary course of nature — they help to strengthen ihe popular misapprehension that plants grow directly out of the soil. Manures consist chiefly of compounds of nitrogen, phosphorus, and pot- ash. These are the things of which the plants take most from the soil ; a-nd when the crops are cut down and carried away, it becomes necessary to restore them. This is generally done by means of farmyard manure, bones, or guano. Most manures are really the remains or droppings of animals ; so that when we lay them on the soil, we are merely returning to it in another form what the animal took from it when he eat the plants up. All plants, however, do not equally exhaust the soil of all necessary materials. Some require one sort of food, and others another. That is why farmers have recourse to what is called rotation of crops, so as to follow up one sort of plan^ in a field by ..nother, whose needs are different. Thus corn is alternated with swedes or turnips. Virgin soil will produce crops for several seasons together without the need for manuring ; but when many crops have been out from it in succession, the earth gets exhausted of nitrates and phosphates, and then it becomes necessary to manure and to rotate the crops in the ordinary manner. HOW PLANTS DBIMX. 67 But in nature crops are not, as a rule, removed from the soil ; they die and wither, and return to it for the most part whatever they took from it. The dead birds anf* insects, and the droppings of animals, are sufficient manure for the native woodland. Still, even in nature, certain plants more or less exhaust the soil of certain valuable materiaL; and therefore natural selection has secured a -ort of roundabout rotation of crops m a way c /hich I shall have more to say here- after. Many plants, for example, which greatly exhaust the soil, ha\ . winged or feathery seeds ; and these seeds are carried by the wind to fresh spots, where they ahght and root themselves, in order to escape the exhausted soil in the neigh- bourhood of their mothers. Other plants send out runners, as they are called, on long trailing branches, which root at a distance, and so start fresh Hves in unexhausted places. Yet others have tu'.ers, which shift their place from year to year ; or they push forth underground suckers, which become new plants at a distance f r- n the parent. All these are different natural w ys for obtaining what is practically rotation of crops ; nifciure invented that plan millions and millions of years before it was discovered by European farmers. Moreover, nature sometimes even goes in for deliberate manuring. Plants like buttercups and daisies, ihat live in ordinary meadow soils, to be sure, get enough nitrogen and sulphur and other such constituents from tlie mould in which they are rooted. But in verj'- moist HOW PLANTS DRINK. 69 and boggy soilg there is generally a lack of these necessary earth- given elements of protoplasm ; and natural selection has ihftrftfore favoured any device in the plants which grow in such places for obtaining them elsewhere. This they do as a rule by catching insects, killing them, sucking their juices, *and using them up af, manure for manufacturing their own protoplasm and chlorophyll. Our pretty little English sundew is one of these cruel and perfidious plants (Fig. 10). Its leaves are round, and thickly covered with small red hairs, which are rather bulbous at the end, and very sticky. The bulbous expansions, in point of fact, are small led glands, which exude a viscid digestive liquid. When a small fly ahghts on the* leaf, attracted by the smell of the sticky fluid, he is caught and held by its gummy mass ; the hairs then at once bend over and clutch him, pouring out fresh slime at the same time, which very shortly envelopes and digests him. In the course of a few hours the leaf has sucked the poor victim's juices, and used them up in the manufacture of its own protoplasm. Many other insect-eating plants exist in the marshy soils of other countries. One of the best-known is the Venus' s fly-trap of tropical or subtropical North America. In this curious plant the leaf is divided into two portions, one of which forms a jointed snare for catching insects. It is hinged at the middle ; and when a fly lights, upon it, the two edges bend over upon him, and the bristles on the margin interlock firmly. As long as the insect struggles 70 THE STORY OP THE PLANTS. (11 they remain tightly olosed; when he ceases to move, and is quite dead, they open once more, and set their trap afresh for another insect. A great many such carnivorous and insectivorous plants are now known : and in almost every case they inhabit places where the marshy and waterlogged soil is markedly wanting in nitrogen compounds. Insect- eating leaves are thus .a device to supply the plant with nitrogen by means of its foliage, in circumstances where the roots prove powerless for that purpose. Simpler forms of the same sort of habit may be seen in many other familiar plants. Thus our Er^glish catchflies and several other of our common weeds have sticky glandular stems, which exude a viscid secretion, by whose aid they catch and digest flies. This is the begin- ning of the insect-eating habit, more fully evolved by natural selection in marsh-plants like sundew, and especially in larger subtropical types like the Venus's fly-trap. If you collect English wild-flowers you will soon perceive that a great many of them have sticky glands on the summit of the stem, near the flowering heads ; and this is useful to them, because the flowers and seeds are particularly in want of nitrogenous matter for the pollen and ovules and the de- velopment of the seed. In short, though plants get their nitrogen mainly by means of the roots, they often lay in a supplementary store by their stems and their foliage. Our common English teasel shows 'ts the beginnings of another form of insect-eating, which is highly developed in certain American How PLANTS DRINK. 71 and Asiatic marsh-plants. The loaves of teasel grow opposite one another, joining the stem at the base, so as to form between them a sort of cup or basin, which will hold water. If you look close into this water you will find that it is often full of dead midges and ants ; and the plant puts forth long strings of living protoplasm into the water, which suck up the decaying juices of these insects, and use them for the manufacture of more protoplasm and chlorophyll. In this case, water is used both as a trap and as a solvent; the insects are first drowned in the moat, and then allowed to decay and digest themselves in it. Teasel, however, is but a simple example of this method of insect-catcl Ing. Several American marsh-dwellers, collectively known as pitcher- plantSf carry the same device a great deal further. They are far more advanced and developed water-trap setters. The Canadian side-saddle plant allures insects into its vase- shaped leaves, which are filled with sugar and water. This is just the same plan which we ourselves employ to catch flies when we trap them in a glass vessel by means of a sweetened and sticky liquid. The pitchers are formed by leaves which join at the edges; they are at- tractively coloured, so as to allure the flies ; and they secrete on their walls a honeyed liquid, which entices the victim to venture further and further down the fatal path. But the inner sides of the vase are set with stiff downward -pointing hairs, which make it easy to go on, but im- possible to crawl back again. So the flies creep 72 THE STORY OP THE PLANTS. down, eating away at the sticky sweet-stuff as they go, till they reach the bottom and the hungry water, when they fall in by hundreds, FIG. 11. — AN AUSTRALIAN PITCHER PLANT WHICH EATS INSECTS. and are drowned and digested. I have found these plants often by the sides of Canadian bogs, with a whole seething mass of festering and T I Fia. 12. — INBECT-EATINO PITCHERS OF THE MALAYAN NEPENTHES. 74 THE STORY OP THE PLAKT8. deoaying insects filling up every one of their murderous vases. Other pitoher-plants are found in Australia (Fig. 11). The Nepenthes of the Malayan Archipelago is a still more remarkable water-trap insect-eater, in which the pitcher is formed by a curious jug- like prolongation at the end of the leaf (Fig. 12). It is provided with a lid, and its rim secretes a sticky sweet liquid. Insects that enter the jug are prevented from escaping by strong recurved hooks ; and these hooks are so powerful that at times they have been known even to capture small birds which had incautiously entered. This may seem curious, but it is not odder than the tact inat our own English bladderwort, a water plant with pretty yellow flowers, which grows in sluggish streams, has submerged bladders that supply it with manure, not only from water- beetles, larvae, and other insects, but also from trout and other young fry of freshwater fishes. I may add that while the sundew and other live- insect catchers have to di^^est their prey, the water- trap makers save themselves that additional trouble and expense by macerating and soaking it till it reaches the condition of a liquid manure, ready dissolved for absorption, and easy to .ussimilate. Thus we see that while roots are the dhiet organs for absorbing nitrogenous matter, they are often supplemented in special circumstances by leaves and stems. Moreover, in many cases leaves also supply the plant with water. On the other hand, roots often fulfil yet another function, HOW PLANTS DRINK. 75 by storing up food for the plant from one season to another. It is true this is still more often done by underground stems, but the distinction between the two is very technical, and I do not think I need trouble you here with it. Large trees with solid trunks usually lay by their Btarch and other valuable materials over winter in a peculiar living layer of the bark; and here it is on the whole fairly free from danger. Still, even in trees the lower part of the bark is often nibbled by such animals as rabbits; and to prevent this mischance most smaller plants bury their rich food-stuffs underground during the cold season. For whatever wiU feed a young plant or a growing shoot will also just equally feed an animal. Hence the frequency with which plants make hoards of their collected food-stuffs under- ground, for use next season. The potato is a well-known instance of such underground hoards ; the plant lays by in what are technically sub- terranean branches a supply of food-stuff for next season's growth. These branches are covered with undeveloped buds, which the farmer calls "eyes"; and from each of these eyes (if the potato is left undisturbed, as nature meant it to be) a branch or stem will start afresh next season. It will use up the starch and other foodstuffs in the potato, till it reaches the light; and there it will begin to develop green chlorophyll, and to make fresh starch for itself, and young leaves and branches. An immense number of plants thus lay by underground stores of food for next season's use. Such are the carrot, the beet, and the 78 THE STORY OF TRB PLANTS. turnip. And in every ease the young shoots fcha* f ; 1 iTif, from them use up the starches and otiifci" Cooa-stuffs at first exactly as an animal would do. These stores are often protected against animals by hard coats or poisonous juices. Many well-known examples of sub- terranean stor*r>9 occur among our spring garden flowers, which are for the most part either bulbous or tuberous. The material laid by in the bulb allows them to start flowering early, while annuals and other unthrifty plants have to wait till they have collected enough material in the same year to flower upon. Hyacinths, tulips, daffodils, snowdrops, crocuses, and the various kinds of squills and jonquils are familiar examples of plants which lay by in one year material for the next year's flowering season. But our wild flowers do the same thing quite as much, though less obtrusively. Our earliest spring buttercup is the bulbous buttercup, which has a swollen root-stock, full of rich material ; and this enables it to flower very soon indeed, while the fibrous - rooted meadow - buttercup, which closely resembles it in most other re- spects, has to wait a month later, and then to raise a much taller stem, in order to overtop the summer grasses, which by that time have reached a considerable height. Still earlier, however, is another buttercup-like plant, the lesser celandine, which has material laid by in little pill-like tubers ; and these have given it its curious old English name of pilewort. Other early spring wild-flowers are the wood anemone and marsh- marigold, with rich and thick almost tuberous BOW PLANTS DftlNK. 17 rootstocks; the bulboin wild hyacinth, the tuberous moadow orchid, and the common arum, or "lords and ladies," with its starchy root, very rich in food-stuffs. Indeed, in every case where a plant flowers very early in spring, you may be sure the material for its flowering was laid up by the plant in the previous year — that it is really rather a case of delayed than of very early flowering. This is especially true of trees, like the black- thorn or the flowering almond, whore the flower- buds are usually formed over winter, and only fully developed in the succeeding spring. The same thing happens with gorse ; only here, a few bushes always break into bloom in October or November, while others burst spasmodically into blossom whenever a warm and suuny spell occurs in January or February. The remaining bushes are covered through the winter with hairy brown buds, and burst out in early spring into golden masses of scented blossom. A like arrangement also occurs in many catkins, which are the flowers of certain trees ; the catkins of the hirch and the alder, for example, are always formed in early autumn, though they only break into bloom with recurring warmth in March or April. We have travelled away so far from our original question of How plants drink, that a 8umi.iary of this chapter is even more necessary than usual. Plants drink by means of roots. But they take up by them, not only water, which is their 78 *H1 OTORT OP WW PIiANTi. needful solvent, but also other materialg urgently required for their growth and development. The most important of these materials is oeitaialy nitrogen, which forms an indispensable com- ponent of protoplaHm and chlorophyll. Where, however, the roota do not supply nitrogenous matter in suflicicnt quantities, plants procure it for themselves by means of their leaves or stems, and therefore become inseot-oating* or flesh- eating. Soils get exhausted at times of nitrates, phosphates, and other necessary materials of plant-life. The farmer meets this difliculty by manuring, and by rotation of crops, liature meets it by dispersion of aeeds. Eoots, h'^wever, have other functions besides drinking wa»,er and sucking up with it certain dissolved materials; the chief of these other functions are fixing the plant securely in the ground, and affording a safe place of winter storage for starches and other surplus food-stuffs. Many plants die down almost entirely, above ground, in winter, and keep their raw material in underground reservoirs, most of which are stem-like rather IMAGE EVALUATION TEST TARGET (MT-3) // ^ .^f-^ / S^ m|0 1.0 I.I 1.25 Ui|21 125 ■Hy "^ MM U. ..„ Hill 2.0 18 lA 11 1.6 V ^^ % '^^ '» Ptiotographic Sciences Corporation 23 WEST MAIN STREET WEBSTER, N.Y. 14JB0 (716) 872-4503 m iV iV N> % " race in a poculiar fashion ; for ii has only three sepals, mstead of five, according to the usual pattern ; while, as if to make up for this loss in one part, it has eight petals instead of five in its corolla. I merely mention this fact to show how many small changes occur in different flowers, even within the limits o* the same family. And though most of the true buttercups are yellow, a few are white, euoh as our own water-crowfoot, and the alpine buttercup called bachelors' buttons ; while still fewer are red, like the turban ranunculus of our spring gardens. But besides the true butteicups, we have also a vast group of buttercup-like plants, descen- dants 01 the same primitive five-petaUad an- cestor, and regarded as members of the butter- cup order. In these we can trace some curious -- - -i ▼ARIOUH MAHRIAOR CUSTOMS. 101 gradations. The little winter aconite of our gardens has this peculiarity : the petal and nectary have grown into a sort of tubular honey- cup, much more attractive to greedy insects than the simple scale-bearing petal of the buttercups. But as this involves Toss of expanded colour- surface, the winter aconite has made up for the deficiency by colouring its calyx a brilliart yellow, so as to resemble a corolla. Several other buttercup-like plants have even lost their petals altogether, and make coloured sepals do duty m their place.' The marsh-marigold, for instance, is one of these ; what look like petals m It are really very brilliant yellow sepals. Moreover, as the marsh-maric'old is such a large and handsome flower, it easily attj-aots insects in early spring ; and this has enabled it to effect an economy in the matter of its carpels or female organs. In the buttercups, we saw, these were veiT numerous, and each contained only one seed ; in the marsh-marigold, on the other hand, they are reduced to five or ten, but each contains a large number of seeds. This arrangement enables a few acts of fertilisation iio suffice for the whole flower. You will therefore find as a rule that advanced types of flowers have ^ry few carpels— sometimes only one— and that when they are more numerous they are often comlined mto a single ovary, with one sensitive surface, so that one fertilisation is enough for the whole of them. Three familiar but highly-advanced members of the buttercup group will serve to show the immense changes effected in this respect by J 1 ^^^mj 103 TBB 8T0RY OV TUB FLAMTI. ■pedal insoot fertilisation. They are the oolum- bme, the larkspur, and the monsshood. In the simple hutteroupi, the honey, wo saw, was easily aooespible to many small ipBeots ; but in the winter aconite it wm made mote secure by being kept, as it were, in a sort of deep iar; and in these highest of .he family it is still further hidden away, in special nookb and recesses, Uke ▼iMes ')r pitchers, so as to te only procirable by bees and butterflies/ These higher insects, on the other hand, are the s&fest fertilisers, becatise they have l#»g8 and a proboscis exactly adapted to the work they are meaut for ; and they have also as a ruV a taste for red, blue, and purple flowers, father than for simple white or yellow ones. Hence the bloasoms that specially lay themselves ou^ for the higher insects are sJmost alwayo blue or purple. Columbine still retains the original five sepals and five petals of its buttercup ancestor. But the sepals here are blue or purple, and are displayed between the petals in a most curious manner, ro ae to help in the coloured advertise- ment of the honey. The petals, on the other hand, are turned into long spurred horns, each with a big drop of honey m its furthdst recess, securely placed where only an insect with a very long proboscis has any chance of reaching it. Within these two rows come the numerous stamens ; had within them again a set of five carpels, each many-seeded. The columbine is so secure of getting its seed set by bees or butterflieb uhat it is able to dispense with the extra carpels. <" fAmOUt MAB&IAOl OOMOICB, JL08 Larkapnr oarridt the same devices one ttep fuFther. Ildi^, there are five eepala, coloured blue, and prolonged into a apiir at ftha bate, which covers tht nectaries. Why this outer covering ? Well, in columbine, thievish insects like wasps often eat through the base of the •ptirred sepaln and Qtcol ilie honey, without benefiting tlio plant in any way, a6 they don't come near the stan: h and carpels. Larkspur provides against that d chince by covering its honey with two prctcia've 3uabs ; for within the spur of the sepals lies a spurred nectary made up of the petals, xhe petals themselves are roduced to two, becauae the sepals are coloure. and do all the attractive duty ; and besides, r i these two petals are combined into one, ao a further economy. But the arrjngement of the flower is so admirable for ensuring fe»'tili8ation that tho plant is able still further to dispense with unnecosaary parts ; so many larkspurs have only a single many-seeded carpel. Such re- ductions in the numbers of parts are always a si^n of high development. Where the device, for effecting the work are poor, many servanto are necessary ; where labour-saving improve- ments have been largely introduced, a very few will do the same work, and do it better. Monkshood, ago^in, is another example of the same tendency. Here, tho one-sidedness which we saw in the larkspur reaches a still more advanced development. The upper sepal is formed into a brilliant blue hooa, and it covers two curiously shaped petals, which contain an abundant store of honey. This arrangement is 104 THE BTORY OP THE PLANTS. 80 splendid for fertilisation that the plant is able largely to reduce its number of stamens ; and though it has three carpels, these are combined at the base, thus showing the first step towards a united ovary. I have treated the single family of the butter- cups at some length, because I wished to show you what sort of variations on a single plan were common in nature. We see here a family, built all on one scheme, but altering its archi- tecture and decoration in the most singular degree in its different members. The simplest kinds are circular^ symmetrical, orderly, and yellow; the highest are irregular, somewhat strangely shaped, and blue or purple. This is the general line of evolution in flowers. They begin hke the buttercup; they end like the monkshood. Familiar instances of round or radial flowers, consisting of separate petals, are the dog-rose, the poppy, the mallow, and the herb-robert or wild geranium. Most of these have five sepals and five petals ; but in the poppy the petals are usually reduced to four, and the sepals to two. Again, a good instance of flowers with separate petals which have become one-sided or irregular, instead of circularly symmetrical, is afforded us by the peaflowers, which include the pea, the bean, the sweet-pea, the laburnum, the broom, the gorse, the vetch, and the lupine. This familiar family, known to botanists as the papi- lionaceous or butterfly-like order (I trouble yoa with as few long names as I can, so you must VARIOUS MAARIAOB CUSTOM 8. 105 forgive one or two occasionally), is one of the largest in the world, and includes a vast number of the most useful and also of the most orna- mental species. The structure of the flower, which is very similar in them all, can be easily studied in the broom or the sweet-pea, plants procurable by everybody. There are still five petals, though two of them are united to form a lower portion of the flower, known as the keel ; thee two others at the side are called the wings ; while a broad and often handsomely coloured advertisement-petal at the top of all ia called the standard. The sepals are often com- bmed into a single calyx-piece, though as a rule the calyx still retains five lobes or teeth, a reminiscence of the time when it consisted of five distinct and separate sepals. The stamens are welded together into a sort of long tube ; and the pistil is reduced to a tingle carpel or pod, containing a few big seeds, very familiar to most of us in the case of the pea, the bean, and the scarlet-runner. This shape of flower has proved so successful in the struggle for life that papi- lionaceous plants are now common everywhere, while hundreds of different kinds are known in various countries. Yet closely as the peaflowers resemble one another in general aspect, they have still among themselves a curious variety of marriage customs. I will mention two only. In gorse, a flower which everybody can easily examine, the wings have two little knobs at the sides for the bee to aUght upon. As he does so, the corolla springs open elastically, and dusts him all over with the 106 THE 8T0BT OF THE PLANTS. fertilismg pollen. But once it has burst, it re- mains permanently open, the keel hanging down in a woe-begori way, so that no bee troubles himself again to yisit it. This saves time for the bees, and enables them quicker to fertilise the remaining flowers; for when they see a gorse- blossom " sprung " as we call it, they recognise at once that it has already been fertilised, and they know they can get no food by going there. In the lupine, on the other hand, and in the common little English birdsfoot-fcrefoil, the keel is sharp at the point, and the pollen is shed into it before the flower fully opens. When a bee lights on the knobs at the side, he depresses the keel, and the pollon is pumped out against his breast in the most beautiful manner. I hope my readers will try some of these experiments in summer for themselves, and satisfy their own minds whether these things are so. So far, we have dealt mainly with flowers in which the petals are all still distinct and separate. But in a great many plants, the petals have grown together, so as to form a single piece, a "tubular corolla," as we call it. This arrangement is very well seen in the harebell, the Canterbury bell, the heath, and the con- volvulus. How did such an arrangement arise ? Well, in many flowers even with distinct petals there is a slight tendency for adjacent parts to adhere at the base ; and in certain blossoms this tendency to adhesion must have benefited the plant, because it would allow the proper fertilising insect to get in with ease, and to find VARIOUS MARaiAGBJ CUSTOMS. 107 his way at once to the stamens and stigma or sensitive surface. The consequence is that the majority of the higher plants have now corollas in a single piece; and nost of these are also coloured red, blue, or purple. Still, even now many of them retain marks of the original five IIG. 18. — PIN-EYED PRIMROSE, CUT OPEN SO AS TO SHOW THE ARRANGEMENT OF THE STAMENS AND STIGMA. FIO. 19. — THRUU-EYBD PRIMROSE, CUT OPEN SO AS TO SHOW STA- MENS AND STIGMA. petals. For instance, the harebell has the edge of the corolla vandyked into five marked lobes ; while in the primrose, only the base of the corolla forms a tube or united pipe, the outer part being composed of five deeply-cut lobes, 106 THE STORY OF THE PLANTS. reminiscences of the five original petals. Indeed, some relations of the primrose, such as the pim- pernel and the woodland loose-strife, have the petals only slightly united at the base, and would hardly be noticed by a casual observer as possessing a tubular corolla. There is one marriage custom of the primrose, however, so very interesting that we must not pass it by even in so brief a survey. Most children are aware that we have in our woods two kinds of primroses, which they know respectively as pin-eyed and thrum-eyed. In the pin-eyed form (Fig. 18), only the little round stigma is visible at the top of the pipe, while the stamens, here joined with the corolla-tube, hang out like little bags half-way down the neck of it. In the thrum-eyed form (Fig. 19), on the other hand, only the stamens are visiole at the top of the tube, while the stigma, erected on a much shorter style, occupies just the same place in the tube that the stamens occupied in the sisoer blossom. Now, each primrose plant bears only one form of flower. Therefore, if a bee begins visiting a thrum-eyed form, he will collect pollen on his proboscis at the very base only ; and as long as he goes on visiting thrum-eyed flowers, he can only collect. Without getting rid of any grains on the deep-set stigmas. But when he flies away to a pin-eyed blossom, the part of his proboscis which collected pollen before will now be opposite the stigma, and will fertilise it ; while at the same time he will be gathering fresh pollen below, to be rubbed off on the sensi- tive surface of a short-styled flower in due season. li. VARfOUS MARRIAOB CUSTOMS. 109 Thus every pm-eyed blossoiii r ist always be fertilised by a thrum-eyed, and every thrum-eyed by a pin-eyed neighbour. This is one of the most ingenious arrangements known for cross- fertilisation. Much as I should like to dwell further on these interesting cases, I must hurry on to oor^plete our rapid survey of a great subject. Mowers hke the harebell and the primrose are tubular but regular. Other flowers with a tubular corolla go yet a step further and are irregular also. This irregularity, like that of the monkshood, secures for them in the end greater certainty of fertihsation. Two well- known groups of this sort are the sages, on the one hand, and the fox-gloves, monkey-plants, and snap-dragons on the other. I shall mention only one instance cf special devices for cross- fertihsation in these groups, that of the varioufi sages, beautifully seen in the large blue salvias of our gardens. In this plant there are only two stamens, though most of the group to which it belongs have four, because the excellent ar- rangements for fertihsation make this single pair a great deal more effective than the thirty or forty required by the common buttercup. J^or the stamens are deUcately poised on a Sv>rt of lever, so that the moment the bee enters the flower, they descend and embrace him, as if by magic. While the rtamens alone are ripe, this continues to happen with each flower he visits ; but when he goes away to an older blossom, he finds the stigma ripe, and bending over into the I 110 Tmi 9T0BT OF THB PLANTS. spot previously occupied by the stamens. Yor can try this experiment very easily for yourself by putting a straw or bent of crass down the tube of a garden salvia, when the stamens will at once bend down and embrace it in the way I have mentioned. You must not suppose, however, that all flowers are fertilised by bees and butterflies. Many plants lay themselves out for quite dif- ferent visitors. Take for example our common English figwort. This is a curious, lurid-looking, reddish-brown blossom, shaped somewhat like a helmet, aud it is fertilised almost exclusively by wasps. Its shape and size exactly adapt it for a wasp's head ; and it blooms at the time of year when wasps are numerous. Now wasps, as you know, are carnivorous and omnivorous creatures ; so the figwort, to attract them, looks as meaty as it can, and has an odour not unlike that of decaying mutton. Certain tropical flowers again attract carrion-flies, and these have big blossoms that look like decomposing meat, and smell disgustingly. A South African flower of this sort, the Stapelia, is sometimes cultivated as R curiosity in greenhouses. I have ah-eady remarked on the white flowers which open at night, and attract the moths of twilight • while others again lay themselves out to be fertilised by midges, beetles, and other insect riff-raff. Most of these have the honey displayed on wide open discs, where it can be sipped by insects with hardly any proboscis. In our latitudes it is only insects that so act VABIOUB MARBIAOB 0U8T0MB. Ill as fertiliBers ; but in the tropics the work of fertilisation is often performed by birds, such as humming-birds, sun-birds, and brush-tongued lories. Many of the most brilliant and beautiful among the bell-shaped tropical flowers have been specially developed to suit the tastes and habits of these comparatively large and powerful ferti- lisers. The tongues of all, but especially of the humming-birds, are admirably adapted for suck- ing honey from flowers, as they are long and tubular, sometimes forked at the tip, and often hairy so as to lick up both honey and insects. The length of the beak and tongue varies to a great extent in accordance with the depth of the tube in the flowers they fertilise. Bird and flower, in other words, have each been developed to suit one another. The same sort of corre- spondence may often be observed between in- sects and flowers developed side by side for mutual convenience. One more point I should like to touch upon before I pass away from this part of the subject ; and that is the lines or spots so often found on the petals of highly developed flowers. These for the most part act as honey-guides, to lead the bee or other fertilising insect direct to the nectar. A very good case of this may be seen in an Indian plant which is found in every English cottage garden— that is to say the so-called nasturtium. This beautiful blossom can only be fertilised by humble bees and humming-bird hawk-moths, no other insect in England at least having a proboscis long enough to reach to the bottom of iia TBB 8T0RT OF TBB PLANTS. the very deep spur which holds the honey. Now, humming-bird hawk-moths do not light on a flower, but hover lightly poised on their quivering wings in front of it. So all the ar- rangements of the flower are strictly set forth in accordance with the insect's habit. The calyx consists of five sepals with a very long spur, the end of which, as you can find out by biting it, is full of honey. Then come five petals, not how- ever, all alike, but divided into two distinct seta, an upper pair and a lower triplet. The upper pair are broad and deeply-lined with dark veins, which all converge about the mouth of the spur, and so show the inquiring insect exactly where to go in search of honey. The lower three, on the other hand, have no lines or marks, but possess a curious sort of fence running right across their face, intended to prevent other flying insects from alighting and rifling the flower without fertilising the ovary. This flov/er, too, has two successive stages ; it opens male, with stamens only, which bend upward towards the insect ; later, it becomes female, the stigma opens and becomes forked, and bends down so as to occupy the very same place pre- viously occupied by the ripe stamens. A great many well-known flowers have such lines as honey-guides. If I have succeeded so far in interesting you in the subject, you will find it a pleasant task to hunt them out for yourself in the violet, the scarlet geranium, the spotted orchid, and the tiger hly. So far I ha\e dealt only with the i^arria^ire IfORB MARRIAOI CUSTOMS. lis arrangements of those plants which are fertilised by insects or birds, and which belong to the great group of flowering plants descended from an early common ancestor with five petals. We must next deal briefly with the marriage customs of the msect-fertilised class among the other ^eat group whose ancestor started with but three petals . and after that we must go on to the otbsr mode of fertilisation by mean? ^* the wmd or of self -impregnation. This chapter has consisted so much of special oases that I do not think it stands in the same need of a summary as aU its predecessorg. ( CHAPTER VIII. MOBE MABBIAOB CUSTOMS. Almost aU the flowering plants with which most people are familiar—all, indeed, save the pines and other conifers— belong to one or other of two great mroups or alliances, each remotely descended from a common ancestor. The flowers we have hitherto been considering are entirely those which belong to one out of these two groups— the group which started with rows of live, having five sepals, five petals, five or ten stamens, and five or ten carpels. In several cases, certain of these rows have been simpUfied or reduced in number ; but almc it always we can see to the end some trace of the original fivefold arrangement. This fivefold arrangement is very conspi^^uous in aU the stonecrops, and it 114 THB BTOR? OF THE PLANTS. if may also be well noticed in wild geraniums, and ie^B well iu the strawberry, the dog-rose, and the oinquefoil. In the present chapter, however, I propose to go on to sundry flowers of the other great group which has its parts in rows of three, and to show how they have been affected by insect yisits. 'jLuis will give us a clearer view of the whole subject, while it will also form a general introduction to systematic botany for those of my readers who may be induced by this book to carry their studies in this direction further. Before proceeding, however, there is one little point I , snould iilce to note about the i^vefold flowers, which we shall find much more common in the threefold, and among the vdnd-fertiUsed npecies. This is the separation of the sexes in mfferent blossoms or even on separate plants. All the flowers we ha /e so far conqidered have contained both male and female portions — have been made up of stamens and carpels united together in tne self -same blossom. But many of them, as you will recollect, have not been actively both male and female at the same moment. The stamens ripened first, the sensi- tive surface of the carpels afterwards ; and this, as we saw, tended to promote cross fertilisation. But if in any species all the stamens in certain flowers were to be suppressed or undeveloped, while in other flowers the game thing happened to the carpels, self-fertilisation would become an absolute impossibility, and every blossom would necessarily be impregnated from the pollen of a nMghbour. Natural selection has accordingly^ •fORR MARRIAOR CURTOMR. 116 favoured such an arrangument in a ooneiderable number of the higher plants. In such oases some of the flowers consist of stamens only vath no carpels ; while others consist of carpels alone, with no stamens. But as all are de- scended from ^.ncestors which had both organs combined in the same tlower, remnants of the stamens often exist in the female flowers as naked filaments or barren threads, while remnants of the carpels eoually exist in the male flowers as central knobs without seeds or ovules. The beautiful begonias, so much cultivated in conservatories, give us an excellent example of such sincle-sex flowers. In these nlants th^ males and females are extremely dififerent. Tht male flower has four coloured and petal-like sepals, surroundinff a number of central stamens. The female flower has five coloured and petal-like sepals, surrounding a group of daintily, twisted central stigmas, while at the base of the blossom IS a large triangular ovary, containing the voung seeds or ovules. Usually :be flowers grow in little bunches of three, each bunch consisting of two males and one female. In the pumpkins, cucumbers, and melons, separate male and female flowers also exist on the same plant. The females here may be easily recognised by having an ovary or small unde- veloped fruit at the back of the blossom, which you can cut across bo as to show the young seeds or ovules within it. As the proper insects for fertilising cucumbers and melons do noi live in England, gardeners usually impregnate the 116 Tun 8T0RT OF TOIt Pr.ANTI. female flowers by bringing pollen from the males to them with a oatnol's hair brush. This pro- cess is coriin^cnly known a*} " setting " the melons. Manv other ganlen flowers have separate male and female blossoms, which ^he begin noi- can easily recognise for himself if he takes the trouble to look for th'^ra. In the instances we have hitherto considered, tha male and female bloPBoms live on the same plant. But the best cross* fertilisation of all is that which is secured where the fathers and mothers belong to totally distinct plants, a plan for raoilitating which we have already seen in the common primrose. Well, now, if any species took to producing all male flowers on one plant, and all females ou another, this great end would become absolutely certain, for every blossom would then always be fertilised by the pollen brought from a distinct plant. Many such mstances have accordingly been produced in the world around us by natural selection. Only, the two kinds of plants must always grow in one another's neighbourhood. Hemp, for example, is a case of a plant where such an arrangement already exists ; some plants : ^e male only, while «ome are female. Mistletoe and hops are other well-knowT ^ arces, which the reader should carefully eiai /u> for uimseit at the proper season. All these are fivefold flowers, and I have brought them in here merely because ono of the earliest and simplest threefold flowers we are going to consider has also this peculiarity MORE MA'-RIAOB CUBTOIIi. 117 . of separate sexes. This is the common arrow- head, a plant that p-ows in watery ditches, and a camtal example of the threefold type in its sinipler development. Each flower, whether male or female, has a green calyx of three small sepals, and a white corolla of three much larger and somewhat papery petala (Fig. 20). But the male flowers have in thei. -pntre au indefinite number of clustering stamens; while the female flowers have an equally numerous net of tiny carp-ils. The blossoms grow m whorls on the KO. 20.— I. MALE, AND II, FEMALB WU>WRM OF AliKOWHEAD. flame stem the males above, the females beneath tiiem. At first sight you would think this a bad arrangement because you might fancy pollen from the males would certainly fall or blow out upon the females beneath them. But the plant prevents that catastrophe by a very simple dodge, wnich we shall have occasion to notice in many other parallel cases. The flowers open from below upward ; thus the females mature first, and are fertiUsed by insects which brine to them pollen from other plants alrekody rifled • later on the males follow suit, and their pollen 118 THE STORY OF THE PLANTS. M I i i: is carried off by the visiting insect to the female flowers on the next plant it visits. Indeed, you may gather by this time how great a variety of devices natural selection has produced for securing this great desideratum of fresh blood, or cross-fertilisation., from a totally distinct plant colony. A much commoner Enghsh wild-flower than the arrowhead shows us another form of early threefold blossom. I mean the water-plan- tain (Fig. 21), a pretty feathery weed, which grows by the side of most ponds and lake- lets. In the water- plantain you have a flower of both sexes combined; it consists of three green sepals, FIO. 21.— FLOWER OP WATEF- /^^^^„« o *^^rt+^i^?Tr« PLANTAIN. The male and ^^^:^^^S ^ a protective female parts are in the same calyx ; three delicate blossom. pinky - white petals, forming the corolla; six stamens — that is to say, two rows of three each ; and a number of small one-seeded carpels, exactly as in the buttercup, which occupies, in fact, the corresponding place among the fivefold flowers. But it is not often in the threefold flowers that we get the calyx green and the corolla coloured, as in these simple and very early types. Most often in this great group of plants the calyx and corolla are both brightly coloured, and both alike 1 I MORB MARBIAQB 0U8T0MB. 119 employed as effective advertisements. A good case of this sort is shown in the flowering-rush, a close relation of the arrowhead and the water- plantain, \jut a more advanced and deve- loped plant than either of them. Here the calyx and coroUa, instead of forming two sepa- T'\te rows, are telescoped into one, as it were, and are both rose-coloured. In such cases we speak of the combined calyx and corolla as the perianth (another long word, with which I'dj sorry to trouble you). In each perianths, how- ever, even when all the pieces are of the same size and are similarly coloured, you can see if you look close that three of them are outside and alternate with the others ; and these three are really the calyx in disguise, got up as a corolla. (An excellent example of this arrange- ment is afforded by the common garden tulip.) Inside its six rose-coloured perianth-pieces, the flowering-rush has nine stamens, arranged in three rows of three stamens each. Finally, in the centre, it has six carpels, equally arranged in two rows of three. Here the threefold architectural ground-plan of the flower is very apparent. You may say, in short, that the original scheme of the two great groups is some- thmg like this : five sepals, five petals, five stamens, five carpels ; or else, three sepals, three petals, three stamens, three carpels. But in any instance there may be two or more srch rows of any organ, especially of the stamens; in any instance certain parts may be reduced in number or entirely suppressed; and in any instance calyx and corolla may be coloured THE 8T0RT OF THE PLANTS. alike bo as aimost to resemble a sirgle row or perianth. There is one more point about the flowering- rush to which 1 would like to allude before going on to the other threefold flowers, and that is this. In arrowhead and water-plantain the carpels are very numerous, but each one-seeded. In flowering-rush, on the other hand, which has a larger and handsomer blossom, more attractive to insects, they are reduced to six ; but these SIX have many seeds in each, bo that a single act of fertilisation suffices for eaoh of them. You may remember that among the fivefold flowers we found a precisely similar advance on the part of the marsh-marigcid above the bulbous and meadow buttercups. This sort of advance is common in na^are. Where a flower learns how to produce many seeds in a carpel, it can soon dispense with several of its carpels, because a few now do well what the many did badly Furthermore, in higher plants, there is a tendency for these carpels to unite so as to form what we call a compound ovary, with a single style, when one act of fertilisation suffices for all of them. . Such combinations or labour- saving arrangements obviously benefit both the msect and the plant, and have therefore been doubly favoured by natura) oAlection. We see this advance beautifully illustrated in the largest and lovelieRt family of the threefold flowers, the lily group, which contains a great number of the haxidsoraest insect - fertilised blossoms, and is therefore deservedly an im- mense favourite in flower-gardens. All the lilies i MORS IfABRIAQB OUBTOMS. 121 have a perianth (or combined calyx and corolla) of six almost similar brilliantly-coloured pieces (in which, however, you can still, as a rule, detect the sepals by their habit of overlapping the petals in the bud). Then they have a set of BIX stamens. Inside that, again, they have a smgle ovary, but if you cut it across with a penknife you will see at once it contains three chambers, each as a rule with several seeds; and these three chambers are a memory of the time when the ovary consisted of three separate carpels. From their midst arises a single long style ; but you may observe all the same that it IS made up of three original and distinct styles, because it divides at the top into three stigmas Dr sensitive surfaces. This is the general plan of the lily group; but in certain individual lilies the stigma is undivided, and in others again the parts are increased to four or even to eight, so as to obscure the primitive threefold arrangement. Most of the large and handsome lilies culti- vated in gardens have perianths of separate pieces, such as one knows so well in the tiger- lily, the Turk's-cap lily, and the beautiful Japa- nese lilimn cmratum. They have also abundant honey, stored in a deep groove of the spotted petals, and they are variegated and lined in such a way as to guide insects direct to their store of nectar. But the family has been so successful with the higher insects, and has produced such an extraordinary variety of very beautiful and brilliant flowers, that it is quite impossible to speak of them in detail. A few among them, 122 THE STORY OP THE PLANTS. like our own wild hyacinth, show a slight ten- denoy on the part of the petals and sepals to unite into a bell-shaped tube ; etiU, even here the pieces are really distinct and separate. But m the true garden hyacinth the pieces unite into a tubular perianth, like the tubular corolla of the common harebell, except that in the harebell the tube is formed by the union of the five petals, while in the hyacinth it is formed by the similar union of thrae petals and three sepals. A 'jtiil higher form of the same union is shown us by the liiy-of-the-valley, in which the six perianth-pieces join throughout to form a very beautiful heather -like cup or goblot. Other famihar members of this great lily group, which you ought to examine at leisure for yourself, in order to see how they are built up, are aspa- ragus, Sr^omon's seal, fritillary, tulip, star-of- Bethlehe , squill, garlic, onion, tuberose, and asphodel. The cultivated hlies of ono sort or another to be found in our gardens may be numbered by hundreds. A family of threefold flowers almost as beauti- ful as the lily group, and seldom distinguished from them save by botanists, is that which bears the .pretty Greek name of amaryllids. The amaryllids are lilies which differ from the rest of their kind, in the fact that the perianth, still composed of six pieces, has grown up and arOund the ovary so as to seem to spring from above it, not below it. Such flowers are said to have "inferior ovaries." Tn other respects the amaryUids closely rt,, uible the UUes, having six coloured perianth-pieces, six stamens, and MORE MARRIAOB CUSTOMS. 123 an ovary of three chambers, -vdth one style in common. Several of the amaryllids are such familiar flowers that I shall venture to describe them as illustrative examples. The snowdrop is an amaryllid which blossoms in early spring, and which shows in a simple form the chief features of the family. It has six perianth-pieces, but these are still distinctly recognisable as calyx and corolla. The three sepals are large and pure white, and they enclose the petals , the three petals are dis- tmctly smaller, and tipped with green in a very pretty fashion. The summer snowflake, com- monly cultivated in old-fashioned gardens, is very like the snowdrop, only here the diflference between sepals and petals has disappeared ; all six pieces form one apparent row, white, tipped with green, in a single perianth. " In the daffodils and narcissuses we get a second group of amaryllids more advanced and developed. Here the six perittnth-pieces are almost alike, though they may still be distin- guished as sepals and petals by a careful ob- server. But the perianth, which is tubular below, divides above into six lobes, beyond which it is prolonged again into what is called a crown, whose real nature can only be under- stood by comparison with such other flowers as the campions, where scales are inserted on the tip of the petals. This crown is comparatively little developed in the narcissus and the jonquil; but in the daffodil it has become by fa.r the largest and most conspicuous part of the entu-e flower, so as completely to hide the bee who V 1S4 THB 8T0RT OF THE PLANTg. visitB it. Of course this large cro^n asalstB fertilisation, and is a mark of advance in the daffodil and the petticoat narcissus. I hope these few remarks will induce you to examine many kinds of aarcissus in detail, in order to see of what parts they are compounded. This seems a convenient place to interpose another remark I have loua wanted to make, namely, that the threefold flowers are also for the most part distinguished by having those narrow grass-like or sword-shaped leaves, with parallel ribs or veins, about which I told you when we were dealing with the question of varieties of foliage. The fivefold flowers, on the other hand, have usually net-veined leaves either feather-ribbed or finger-ribbed. And at the risk of using two more horrid long words, I shall venture to add that botanists usually speak of the threefold group as monocotyledons, and of the hvefold group as dicotyledons. I did not invent those words, and I am sorry to have to use them here; but I will explain what they mean when I come to deal with seeds and seedlings. It is well at least to understand their use in case you come across them in your future reading. '' Another family of threefold flowers, closely allied to the rmaryllids, is that of the irises, many examples of which are fcmiliar in our flower-gardens. It only differs from the ama- ryllids, in fact, in having the number of stamens still further reduced to three, which is always a sign of advance, because it shows that the plants are so sure of fertiUsation as to be able HORB IfARRIAGV OUSTOMB. 12(S I to dispense with all unnecessary pollen. The ovary is also inferior, which you will learn in time to recocnise as a constant sign of high development, because it means that the base of the corolla and calyx have coalesced with the carpels, and so ensured greater certainty of fertilisation. Some simple members of the iris group, like the crocuses, have mere tubular flowers, with a very long funnel-like base to the corolla, and with the ovary buried in the ground for greater safety. They are early spring blossoms, which need much protection against cold; therefore they thus bury their ova- ries, and sheathe theli flower-buds m a papery covering, composed of a thin and leathery leaf. Whenever a sunny day comes in winter the bees venture out ; and on all such days, even though it freeze in the shade, the crocuses are open in the sunshine to welcome them. But other irises are more complicated, like the gladiolus, and sMU more tL j garden irises, m which the difference between the calyx and corolla is carried to its furthest point in this family. The sepals in true irises are large and brilliantly coloured ; they hang over gracefully ; the petals are smaller and erect; the stigmas are so expanded as to look like petals; and they arch over the stamens in a most peculiar manner. If you watch a bee visiting a garden iris, you will see for yourself the ise of this most peculiar arrangement; the bee lights on the bending sepal, and inserts his head between the stigma and the stamen in a way which renders fertilisation simply inevitable. But the 126 THE STORY OP THE PLANTS. [ most curious part of it all is that the flower, from the point of viow of the bee, resembles three distinct and separate biossoms ; he alights one after another on each bending sepal, and proceeds to search for honey as if in a new flower. Highest of all the threefold flowers, and most wonderful in their marriage customs, are thd I FIC. 22. — SINGLE FLOWER OF ORCHID, WITH THl PERIANTH CUT AWAY. The hoDcy is in the spur, n; the pollen-masses are marked a; their gummy base is at r; the stigma at st. great group of orchids, some of which grow wild in our English meadows, while others fix them- selves by short anchoring roots on the branches of trees in the tropical forests. Many of these last produce the handsomest xnd most extra- ordinary flowers in the world, and they are MORS MARRIAGR OUftTOUB. 1 137 muoh oulfcivated acoordinglv in hothouses and oonservatorieB. It would be quite impossible for me to give you any account of the infinite devices invented by these plants to secure insect-fertilisation ; and even the structure of the flower is so extremely complex that I can hardly undertake to describe 't to you intel- ligibly ; but I will give you such a brief state- ment of its ohiei peculiarities as will enable you to see how highly it has been specialised in adaptation to insect visits. The ovary in orchids is inferior, and curiously twisted. It supports six perianth-pieces, three of which are sepals, often long and very hand- some ; while two are petals, often arching like a hood over the centre of the flower. The third petal, called the lip, is quite different in shape and appearance from the other two, and usually hangs down in a very conspicuous manner. There are no visible stamens, to be recognised as such; but the pollen is contained in a pair of tiny bags or sacks, close to the stigma. It is united into two sticky club-shaped lumps, usually called the pollen-masses (Fig. 22). In other words, the orchids have got rid of all their stamens except one, and even that one has united with the stigma. I will only describe the mode of fertilisation of one of these plants, the common English spotted orchis; but it will suffice to show you the extreme ingenuity with which members of the ' mily often arrange their matrimonial alliances. The spotted orchis has a long tube or spur at the base of its nopals (Fig. 22, n), and 128 THE 8T0RY OP THPJ PLANTS. this spur contains abundant honey. The poUon- rnassos are neatly lodged in two little sacks or pockets near the stigma, and are so placed that their lower ends come against the bee's head as he sucks the honey. These lower ends (r) are gummy or viscid, and if you press a tjtraw or the point of a pencil against them, the pollen- nxasses gum themselves to it naturally, and comb readily out of their sacks as you withdraw the pencil (Fig. 23). In the same way, when no. 23.— POLLEN- MABSE8 OF AN ORCHID, WITH- mu WN ON A PENCIL. In I, they have just been removed. In II, they have dried and moved forward. the bee presses them with his head, the poUen- masses stick to it, and he carries them away with him as he leaves the flower. Just at first, the pollen-masses stand erect on his forehead; but as nies through the air, they dry and contract, so that they come to incline forward and out- ward By the time he reaches another plant they have assumed such a position that they are wrought into contact with the stigma -s he sucks the honey. But the stigma is gummy too. and makes the poUen adhere to it, and in this IfOnE MARftlAOE CUSTOITC. 1» way cross-fertilisation is endered almost a dead certainty. Tho result of these various clever dodges IS that the orchids have b(3coine one of the dominant plant-families of tho world, and in the tropics UBurp many of the best and most favoured positions (Fig. 24). Darwin has written a moHt romantic book on the numerous devices by which orchids alone attract msects to fertilise them. I will aay no more of this family, therefore — the highest and strangest aKiong the threefold flowers — aave mwrely to advise those who wish to know more of this curious subject to look it up in his charming volume. Instead of pursuing the matter at issue further, I will give one final example in an opposite direction. An opposite direction, I say, because all the threefold flowers we have hitherto been considering are exa? i of a strict upward move- ment of evolution. Each group we have ex- amined has been higher and more complex than the group before it. But I will now show you an instance, if not of degeneracy, at least of extreme simplification, which yet produces in the end the best j, "ssible results. This instanc . IS that of the common English arum, known to children as cuckoo-pint or " lords and ladies " (Fig. 25). FIO. 24.— THE TWO P0LLEN-MA88E8, VERT MUCH ENLABOED. 180 THE STORY OF THE PLANTS. The structure of tha ouckoo-pint is very peculiar. What looks like the flower is not really any part of the flower at all, but a large FIO. 26. — TflE COMMON ARDM, OR CDCKOO- PINT, SHOWING THE 8PATHE WHICU PUR- •R00ND8 THB FLOWERS, AND TUB SPIKK 8TICKIN0 UP IN THE MIDDLE. outer leai or spathe surrounding a group of very tiny blosBoms. You can understand this leaf better if you look at a narcissus stalk, where klORB KASRUOB OtTSTOAIS. 131 very ( not largo very leaf rhere :i very flimilar leaf is Men to enoloic » whole bunch of buds and opening flowen. Only, in the narcissus the spathe ie thin, whitish, and papery, while m the cuckoo-pint it is expanded green, and purple. Though not a corolla, it ■erves the same purpose as a corolla generahy performs: it attracts insects to the compound flower-head. Inside the spathe we find a curious club-shaped mass, coloured bright purple, and standing straight up in the middle of the head. This is the stem or axis on which the separate little flowers are arranged. Cut open the spathe, and you will 5nd thepe flowers below in the centre (Fig. 26). At first sight what you see will look like a lot of confused little knobs; but when you "jaze closer you will see they separate themselves into three groups, which are the true flowers. Lowest of all on the stem come the female blosso i.s, without calyx or corolla, each consisting of a single ovary. Abo» 'hese in a group come the male flowers, equally devoid of calyx or corolla, and each con- sistmg of a single stamen. Above these again °°J^6 abortive or misshapen flowers, each of which has been reduced to a single downward- pointmg hair. I will explain first what is the 5^ H •■" U 11 use of these flowers in the cnokoo-pint as it stands to-day, and then I will go back to con- side ^^ by what steps the plant came to develop theiii. The upper flowers, which look like hairs, and point all downwards, occupy a place in the compound flower-head just opposite the con- spicuous narrowed part of the spathe which surrounds and encloses them. At this narrow point they form a sort of lobster-pot. It is easy enough for an insect to creep down past them, but very difficult or impossible for him to creep up in the opposite direction, as all the hairs point , sharply downward. Now, when the spathe unfolds, large numbers of a very small midge of a particular species are attracted into it by the purple club which rises like a barber's pole in the middle. If you cut a cuckoo-pint open during its flowering period you will always find a whole mob of these wee flies, crawUng about in it vaguely, and covered from head to foot with pollen. They ht ) come from another cuckoo-pint which they previously viftited, and they have brought the pollen with them on their wings and bodies. But when they first reach the head, they find no pollen there ; the female flowers at the bottom ripen first, and the midges, creeping over the sensitive surface of these, fer- tilise them with pollen from the last plant they entered. Finding nothing to eat, if they could they would crawl out again ; but they can't, for the lobster-pot hairs prevent them. So they stop on perforce, having unwittingly fertilised the female flowers, but received themselves as MORE MAKBIAQE CUSTOMS. 183 vet no reward for their trouble. By and by, nowevei , after all the female flowers have been duly fertilised, the males above begin to ripen. When the stamens reach maturity, they shower down a whole flood of golden pollen on the expectant midges. Then the midges positively roll and revel in the flood, eating all they can, but at the same time covering themselves all over with a dust of pollen-grains. As soon as the pollen is all shed, the downward-pointing hairs wither away; the lobster-pot ceases to act; and the midges are at liberty to fly away to another plant, where they similarly begin to fertilise the female flowers. Observe that, if the stamens were the first to ripen here, the pollen would fall on the stigmas of the same plant, but that, by making the stigmas be the first to mature, the cuckoo-pint secures for itself the desired end of cross-fertilisation. In this case it is an interesting fact that all the stages which led to the existing arrangement of the flowers still remain visible in other plants for us. These very reduced little blossoms of the cuckoo-pint, consisting each of a single carpel or a single stamen, are yet the descendants of per- fect blossoms which had on(;e a regular calyx and corolla. Near relations of the cuckoo-pint Uve in Europe and Africa to this day, which recapitulate for us, as it were, the various stages in its slow evolution. Some, the oldest in type, have a calyx and corolla, green and inconspicu- ous, with six stamen? inside them, enclosing a two or three-celled ovary. These are still essen- tially lilies in structure. But they have the 134 THE STORY OP THE PLANTS. flowers clustered, as in cuckoo-pint, on a thick club-stem, and they have an open spathe, which more or less protects them. Our English sweet- sedge is still at this stage of evolution. The marsh-calla of Northern Europe and Canada, on the other hand, has a handsome white spathe to attract insects, while its separate flowers, still both male and female together, ha/e each six stamens and a single ovary. But they have lost their perianth. The common white arum or "cttUa lily" of cottage gardens has a bright yellow spike in its midst, and if you look at it closely yo will see that this spike consists entirely of a great cluster of stam ns, thickly massed together. The top of the spike is entirely composed of such golden stamens, but lower down you will find ovaries embedded here and there among them, each ovary as a rule sur- rounded by five or six stamens. Lastly, in the cuckoo-pint the lower flowers have lost their com- pTej.aent of stamens altogether, while the upper ones have similarly lost their ovaries ; moreover, a few of the topmost have been converted into the curious lobster-pot hairs which assist, as I have shown you, in the work of fertiUsation. We have here a singular and instructive example of what may be described as retronrade develop- ment. And now we must go on to those modes of fertilisation which are effected by agencies other than insects. CHAPTER IX. THB WIND AS OABBIEB. All flowers do not depend for fertilisation npon insects. In many plants it is the wind that serves the purpose of common carrier of pollen froa blossom to blossom. Clearly, flowers which lay themselves out to be fertihsed by the wind will not be likely to produce the same devices as those which lay themselves out to he fertilised by insects. Natural selection here will favour different quali- ties. Bright-coloured petals and stores of honey will not seiTC to allure the unconscious breeze - such delicate adjustmc nts of part to part as we saw in the case of bee and blossom will no longer be serviceable. What will most be needed now is quantities of pollen ; and that pollen must hang out in such a way from the cup as to be easily dislodged by passing breezes. Hence wind-fertilised flowers differ from insect-ferti- lised in the following particulars. They have never brilliant corollas or calyxes. The stamens are usually very numerous; they hang out freely on long stalks or filaments ; and they quiver in the wind with the slightest movement. On the other hand, the stigmas are feathery and protrude far from the flower, so as to catch every passing grain of pollen. More frequently than among the insect-fertilised section, the sexes are separated on different plants or isolated in dis- tinct masses on neighbouring branches. But 186 136 TH2 STORY OF THF PLANTS. numerous devices occur to prevent self-fertili- sation. You must not suppose, again, that the wind- fertihsed plants form a group by themselves, distmot in origin from the insect-fertilised, as the three-petalled group is distinct from the fiye-petalled. On the contrary, wind-fertilised kmds are found abundantly in both great groups ; it is a matter of habit ; so much so that sometimes a type has taken first to insect-fertili- sation and then to veind-fertilisation, with com- paratively slight differences in its external appearance. Closely related plants often differ immensely in their marriage customs ; each has varied ifi the way that best suited itself, accord- ing as insects or breezes happened to serve it most readily. In my own opiniorj all wind- fertilised plants are the descendants of insect- fertilised ancestors ; but I do not know whether in this oelief my ideas would be accepted by most modern botanists. As a first example of wind-fertilised flowers, I will take the common dog's mercury, a well- known English wayside flower, frequent in copses and hedgerows, and one of the very earliest to blossom in spring. lu this species the males and females grow on separate plants. They have each a calyx of three sepals (two more -being suppressed, for they belong by origin to the fivefold division). The males have ten or twelve stamens apiece, which hang out freely with long stalks to the breeze. The females have a two-chambered ovary, with rudiments or relics of some two or three THE WIND AS CARRIER. 137 Btamans by its side, showing that they are descended from earlier combined malo-and- female ancestors. The relics, however, consist of mere empty stalks or filaments, without any pollen-sacks. Of course there are no petals. Male and female plants grow in little groups not far from one another ; and the pollen, which is dry and dusty, is carried by the wind from the hanging stamens of the males to the large and salient stigma of the female flowers. A still better ex- ample of a wind- fertilised blossom is afforded us by the common English salad - burnet, a pretty little weed, very frequent on close-cropped chalk downs (Fig. 27). Here the individual fig. 27.,— A, male, and B, female flowers are ez floweb op salad-burnet, very tremely smaU, and "^""^^ magnified. The flowers +l,^,r Lr. J J g'^^w together in little tasspl- they are crowded nk© heads. into a sort of mop- like head at the top of the stem. They have lost their petals, which are now of no use to them ; but they retain a calyx of four sepals, to represent the original five still found among their relations. For salad-burnet, in spite of its .nconspicuous- ness, bel mgs to the family of the roses, and we can still trace in this order a regular gradation from handsome flowers like the dog-rose, through .88 THB BTOBT OF THE PLANTS. smaller and smaller blossoms like vhe strawberry and the potentilla, to green petalless types like lady's-mantle and parsley-piert, or, last of all, to wind-fertilised blossoms like those of the salad- burnet. In the male flowers the very numerous stamens hang out on long thread-like stalks from the wee green cup, so that the wind may readily catch and carry the pollen: in the female blossoms the stigma is divided into plume-like brushes, which readily entrap any passing pollen-grain. Moreover, though both kinds of flower grow on the same head, the females are mostly at the top of the bunch, and the mal^s below them. This makes it difficult for the pollen from the same head to fertilise the females, as it would easily do if the males were at the top. Nor is that all ; the female flowers open first on each head, and hang out their pretty feathery stigmaj to the broeze that bends the stem ; as soon as they have been fertilised from a neighbour plant, the males in turn begin to open, and shed their pollen for the use of other flowers. In salad-burnet, however, the division of the sexes into separate flowers has not become a quite fixed habit; for, though most of the blossoms are either maleor female only, as shown in the figure, we often find a cup here and there which contains both stameiiS and pistil together. I have already told you that in many plants the calyx helps the corolla as an advertisement for insects ; and sometimes, as in the marsh- marigold and the various anemones, where there are no petals at all, it becomes so brilliant as to THE WIND AS CARRIER. 139 be mistaken for petals by all but botanists. One w weeds hke the hawkbit and the sow- thistle. A few are cultivated as vegetables, such as lettuce, salsify, chicory, and endive ; fewer still are prized for their flowers for ornamental purposes, such as the orange hawk- weed. The prevailing colour in this class is yeUow, and the devices for insect-fertilisation are not nearly so high as in the ray-bearing group. I regard them as to a great extent a retrograde tribe of the composite family. In this chapter I have d< ait chiefly with the co-operative clubbing toget) n of insect-fertilised flowers, for purposes of muoaal convenience ; but you must not forget that similar clubs exist also among the wind-fertilised blossoms in quite equal profusion. Such are the catkins of forest trees, the panicles of grasses, the spikes of sedges, and the heads of the black-cap rush and many other water-plants. Some of these, such as the bur- reed, we have akeady considered. Lastly, I ought to add that where the flowers themselves are inconspicuous, attention is often caUed to them by a bright-coloured leaf or group mm 162 THE 9T0BY OF THB PtANTfl. of leaves in their immediate neighbourhood. We saw an instance of this in the great white spathe or folding leaf which encloses the male and female flowers of the "calla lily." In the greenhouse poinsettia the individual flowers are tiny and unnoticeable ; but they are rich in honey, and round them has been developed a great bunch of brilliant scarlet leaves which renders them among the most decorative objects in nature. A lavender that grows in Southern Europe has dusky brown flowers; but the bunch is crowned by a number of mauve or lilac leaves, hung out like flags to attract the insects. A scarlet salvia much growh in windows similarly supplements its rather handsome flowers by much handsomer calyxes and bracts which make it a perfect blaze of splendid colour. It doesn't matter to the plant how it produces its effect; all it cares for is that by hook or by crook it should attract its insects and get itself fertilised. CHAPTER XI. WHAT PLANTS DO FOR THEIR YOULJ. After the flower is fertilised it has to set its seed. And after the seed is set the plant has to sow and disperse it. Now, the fruit and seed form the most difficult part of technical botany, and I will not apologise for treating- them here a little cavalierly. I will tell you no more about them than it is actually WHAO? PLANTS DO FOB THJSIB YOUNO. 163 necesgary you should know, leaving you to pursue the subject if you will in more forme.! The pistil, after it has been fertilised and arrived at maturity, is called the fruit. In flowers like the buttercup, where there are many carpels, the fruit consisl^s of distinct parts, each one-seeded little nuts in the meadow buttercup, but many-seeded pods in the marsh- mangold and the larkspur. Where the carpels have combined into a single ovary, we get a many-chambered fruit, as in the poppy, which consists, when cut across, of ten seed-bearing chambers. Most fruits are dry capsules or pods, either single, as in the pea, the bean, the vetch, and the laburnum ; or double, as in the wallflower and shepherd's-purse; or many-chambered, as m the hly, the wild hyacinth, the poppy, the campion. As a rule the fruit consists of as many carpels or as many chambers as the unfertilised ovary. Fruits are often dispersed entire, and this is especially true when they contain only one or two seeds. In such instances they sometimes fall on the ground direct, as is the case with most nuts ; or else they have wings or para- chutes which enable the wind to seize them, and carry them to a distance, where they can ahght on unexhausted soil, far away from the roots of the mother plant. Such fruits are common among forest trees. The maples, for example, have a double fruit, often called a Key, which the wind whirls away as soon as the seeds are ready for dispersion (Figs. 37, 38, 39, 8^ 164 THE STOBY OF THE PLANTS. 40, 41). In the lime, the common stalk of the flowers is winged by a thin leaf ; and when the I o 6 i 00 .CO 6 CO M Pn3 i « 2 « o M CO es rmed by the part that was common to manj' of the leaves, like a midrib. The accc ;,^-.nying diagram (Fig. 49) will make this clea ii chan any amount of description could possibly make it. Starting from such a point, certain r:l.:ints would soon find they were iihuB enabled to overtop others, and to obtain freer access to light and carbonic FIG. 49. — FIRST STEPS IN THE EVOLUTION OF T' J. STEM. l!^ I I '. f •li I 178 THE 8T0KT OF THB PLANTS. acid. Gradually, natural selection would ensure that the common central part of the growing plant, the developing stem, should oecome harder and more resisting than the rest, so as to stand up against the wind and other opposing forces. At last there would thus arise a clearly- marked trunk, simple at first, but later on branching, which would lift the leaves and flowers to a considerable height, and hang them out in such a way as to catch the sunlight and air to the best advantage, or to attract the fertilising insects or court the wind under the fairest conditions. I leave you to think out for yoi^rself the various stages of the process by which liatural seleo.tion must in the end secure these desirable objects. In order to understand the nature of the stem, in its fully developed form, however, we must remember that it has three main functions. The first is, to raise the foliage, with the flowers and fruits as well, visibly above the surface of the ground on which they grow, so that the leaves may gain the freest possible access to rays of sunlight and to carbonic acid, while the flowers and fruit may receive the attentions of insects and birds, or other fertilismg and dis- tributing agents. The second is, to conduct from the root to the foliage and other growing parts what is commonly called the raw sap — that is to say, the body of water absorbed by the rootlets, together with the nitrogenous matter and food-salts dissolved in it, all of which ore needed for the ultimate manufacture '11 i THE BTBBf AND BRANOHBB. 179 of protoplasm and chlorophyll. The third is, to carry away and distribute the various matured products of plant life, such as starches, sugars, oils, and protoplasm, from the places in which they are produced (such as the leaves) to the placeo where they are needed for building up the various parts of the compound organism (such as the flowers and fruit or the growing shoots), as well as to the places where such materials are to be stored up for safety or for future use (as, for example, the tubers and roots, or the buds, bulbs, and other dormant organs). Each of these three essential functions we must now proceed to consider separately. ♦ In order to raise the leaves and branches visibly above the ground into the air above it, the stem is made much stronger and stouter than the ordinary leaf-tissue. If the plant does not rise very high above the ground, indeed, as in the case of small herbs, and especially of annuals, its stem need not be very hard or stiff, and is often in point of fact quite green and succulent. But just in proportion as plants grow tall and spreading, carry masses of foliage, and are exposed to heavy winds, do they need to form a stout and woody stem, which shall support the constant weight of the leaves, or even bear up under the load of snow which may cover the boughs in wintry weather. Thus, a tapering tree like the Scotch fir requires a com- paratively smaller stem than an oak, because its branches do not spread far and wide, while its single leaves are thin and needle-like ; whereas 180 THE STORY OP THE PLANTS. k I the oak, with its massive boughs extending far and wide on every side, and covered with a weight of large and expanded absorbent leaves, requires a peculiarly thick and buttressed stem to support its burden. Both in girth and in texture it must differ widely from the loose and swaying pine-tree. Every stem is thus a piece of ingenious engineering architecture, adapted on the average to the exact weight it will have to bear, and the exact strains of wind and weather to which on the average it may count upon being exposed in the course of its life- history. We see the result of occasional failure of adaptation in this respect aftar every great storm, when the corn in the fields is beaten down by hail, or the fir-trees in the forest are snapped off short like straw by the force of the tempest. But the survivors in the long run are those which have succeeded best in resisting even such unusual stresses ; and it is they that become the parents of after generations, which of course inherit their powers of resistance. Most stems, at least of perennial plants, and all those of bushes, shrubs, and forest trees, are strengthened for the purpose of resisting such strains by means of a material which we call wood. And what is wood ? Well, it is an extremely hard and close-grained tissue, manu- factured by the plant out of its ordinary cells by a deposit on their walls of thickening matter. This process of thickening goes on in each cell until the hollow of the centre is almost entirely filled up by the thickening material, leaving only a small vacant space in the very middle. The THE STEM AND BBANOHBS. 181 thickening matter, which consists for the most Eart of carbon and hydrogen, is built up there y the protoplasm of the cell itself : but as soon as the process is quite complete, the protoplasm emigrates from the cell entirely, and goes to some other place where it is more urgently needed. Thus wood is made up of dead cells, whose walls are immensely thickened, but whose living contents have migrated elsewhere. In large perennial stems, like those of oaks and elms, a fresh ring of wood is added each year outside the ring of the last growing season. This new ring of wood is interposed between the bark (of which J shall speak presently] and the older wood of the core or heart, wnich was similarly laid down when the tree was younger. In this way, the i. umber of rings, one inside another, enables us roughly to estimate the age of a tree when we cut it down ; though, strictly speaking, we can only tell how many times growth in its trunk was renewed or retarded. Still, as a fair general test, the number of rings in a trunk give us an approximate idoa of the age of the individual tree that produced it. The principle is only true, however, of the great group of dicotyledonous trees, such as beeches or ashes, as well as of the pines and other conifers. In monocotyledonous trees, like the palms and bamboos, the stem does not increase in quite the same way from within outward, and there are therefore no rings of annual growth to judge by. Palms rise from the ground as big or nearly as big at the begin- ning as they will ever be in the end ; and though mm 183 THB 8T0RT OF THB PLAMTl. fifl m each year they rise higher and higher into the air, and produce a fresh bunch of leaves at their summit, they seldom branch, and they never produce large buttressed stems like the oak or the chestnut. The second main function of the stem is to convey the raw sap absorbed by the roots to the leaves and branches, and especially to the growing poircs. This is such a very important element in plant life that we must now consider it in some little detail. If you look for a moment at a great spreading oak-tree, with its top rising forty or tifty feet above the level of the ground, and its roots spreading as far and as deep beneath the earth, you will see at once how serious and difficult a mechanical problem it is for the plant to raise up water from so great a depth to so great a height v/ithout tl ) aid of pump or siphon. For the plant can no more work miracles than you or I can. Yet every leaf must be constantly supplied with water, that prime necessary of life, or it will wither and die ; and every growing part must obtain it in abundance, in order to give that plasticity and freedom which are needful for the earlier constructive processes. Protoplasm itself can effect nothing without the Assistance of water as a solvent for all materials it employs in its operations. How does the plant get over these difficulties ? Well, the stem is well provided with a whole system of upward distributing vessels in which water may be conveyed to the various parts, TBI •TRII AND BRANOHBB. 188 juflt as it is conveyed in towns through the pipes and taps wherever it is needed. But what is the motive power for this mechanical work? How does the plant raise so much liquid to such a considerable height, without the mtervention of any visible and tangible machinery? Two main agents are employed for this pur- pose. The one is known as root-pressure; the other as evaporation. I begin with the former. The cells of which roots are made up are most ingeniously con- structed so as to exert this pecuHar form of pressure. Each one of them has at its outer or free end, where it comes into contact with the moist earth, a wall of such a nature that it very readily absorbs water, and allows the water so absorbed to flow freely through it inward. But once in, the water seems almost as if imprisoned in a pump ; it cannot pass outward again, only inward and upward. You may compare the cell in this respect with those mechanical valves which yield readily to the pressure of fluids from outside, but instantly close when a fluid from inside attempts to pass through them. In this way the outer cells of the hairs on the roots, which come in contact with the moistened soil, get distended with water, and swell and swell, till at last their walls will give no longer, and their own elas- ticity forces the water out of them. But the water cannot flow back ; so it has to flow for- ward. Again, each cell or vessel which the stream afterwards enters is constructed on just the same general principle as the absorbent 184 THE STORY OF TBI PJLAKTI. H root-collB ; it allows water to pan into it freely from below upward, but does not allow it to pau back again frona above downward. Thuo we get a constant state of what is called turgidity in the lower cells ; they are as full as they can hold, and they keep on contracting elastically, so as to expel the water they contain into other cells next in order above them. By means of such root-pressure, as it is called, raw sap is being for ever forced up from the soil beneath into the stem and branches, to supply the leaves with water and food-salts, espocially in early spring, when the processes of growth are most active and vigorous. It is owing to this peculiar property of root- pressure that cut stems "bleed" or exude sap, especially in spring-time. The root-pressure continues of itself in spite of the fact that the stem has been divided; and the sap absorbed by the roots is thus forced out at the other end by the continuous elasticity of the cells and vessels. The fact that severed stems will thus "bleed" or exude raw sap shows in itself the reality of root-pressure. But root-pressure alone would not fully sufiSce to raise so large a body of water as the plant requires to so great a heicht above the earth's surface. ^ It is therefore largely supplemented and assisted by the second or subsidiary power of evaporation. This evaporation, or " transpi- ration " as it is generally called, is just as necessary and essential to plants as breathing is to men and animals. We must therefore enter a little more fully THE BTIII AMD UlUNOHBI. 185 her© Into th^ i^.^ fA^ #< -•^'' / ^^ ^ 1.0 I.I 1.25 Ao 12.0 2,2 A" U 111.6 ^ ^ /^ ^ "c-1 :> > v: jV V c/^ ^ Photographic Sciences Corporation 23 WEST MAIN STREET WEBSTER, N.Y. 14580 (716) 872-4503 •<5 iV v ,m V 6^ red with supplies of starch and other food-stu£fs. It sends up at first a short spreading stem, which twines or trails over surrounding plants, developing as it goes very curious leaves of a compound character. Each leaf consists of five or six pairs of leaflets, placed opposite one another on the common stalk in the feather-veined fashion. But the four or five leaflets at the end of each leaf- stalk do not develop any flat blade at all, and are quite unleaflike in appearance : they are transformed, indeed, into long thin tendrils, which catch hold of neighbouring branches or stems of grasses, twine spirally round them, and 80 enable the vetch to oUmb up bodily in spite .Mi 208 THB BTORT OF THE PLANTS. of its weak stem, and raice its leaves and flowers to the air and the sunlight. At the base of every leaf, again, you will find, if you look, two arrow-shaped appendages, which block the way up the stem towards tha deve- loping flowers for useless creeping insects such as steal the honey withe uu assisting fertilisation. On each appendage is a curious black spot, the use or function ot which is not apparent while the blossoms are in the bud. But after a few weeks* growth, the vetch begins to produce solitary flowers in the angle of each upper leaf; flowers of the usual pea-blossom type, but piuk or reddish purple, and handsome or attractive. These flowers contain abundant honey to allure the { roper fertilising insects. Just as thev open, however, the black spot on the arrow-headed appendages of he lower leaves, in whose angles there are no flowers, begins also to secrete a little drop of honey. What is the use of this device? Well, if you watch the vetch carefully, you will soon see that ants, enticed by the smell of honey in the opening flowers, crawl up the stem in hopes of stealing it.' But ants, as we know, are thieves, not fertilisers. As soon as they reach the first black spot, they stop and lick up the honey secreted by the gland, and then try to pass on to the next appendage above it. But the arrow-shaped barbs, turned back against the stem, block their furthe r progress ; and even if they manage to squeeze themselves through with an effort, they are met just above by another honey-gland and another barrier in the shape of PLANT BIOORaPHIBS. 909 ft iecond arrow-ghaped appendage. No ant ever Seto beyond the third or fourth bftrrioade; tha evioa is efficient : the vetch thui offers black- mftil to creeping thieves in the shape of stem- honey, in order to guard from th*»ir depredations the far more valuable and usefni honey iu the flowers, which is intended to attract the fertihsing insects. When the purple flowers have in due time been fertilised, they produce long narrow pods, etch containing about a dozen round pea-like seeds. As the pods ripen, the plant shrivels up, and usually dies away, leaving only the ripe seeds to represent its kind through the winter. But sometimes, in damp and luxuriant autumns, the stem struggles through the winter to a second season, and flowers again in the succeeding summer. We express this fact as a rule by saying that the vetch is usually an annual, but occasionally a biennial. With most annuals, such as wheat or sun- flower, the whole strength of the plant is us#^d up in the production of seed; and as soon aa the seed is set, the plant dies immediately. Where annuals have the sexes on separate plants, however, the male plants die as soon as they have shed their pollen, their task being thus complete ; while the females live on till their seed has ripened. Common coltsfoot is another well-known plant whoP', life-history shows some points of great interest. It grows in the first instance from a feathery fruit, one-seeded and seed-like, which is carried by the wind, often from a great 14 210 THE BTOHY OF TUB PLANTS. dietanoe. Thuse flying fruiti alight at last upon Bomo patch of baro or newly-tnrned Boil, Buoh as tho bank of a stream ^.here there has been lately a landnlip, or the side o! a railway outting. These bare situations alone suit tha habits of tho baby coltsfoot ; if tho fruit happen*! to settle on a light soil, already thickly covered with luxuriant vegetation, it cannot coir pete against the established possessors. But the winged fruits, being dispersed on every side, enable many young plants to start well in life on the poor stiff clays which host suit the con- stitution of this riverside weed. The seedling grows fVist in such circumstances, and soon pro- duces large angtilar leaves, very broad and thick, which in the adult plant have often a diameter of five or six 'nches. They are green above, where they catch the sunlight and devour carbonic acid ; but underneath they are covered with a thick white wool, which is there for a curious and interesting purpose. The damp clay vallevs and river glens where coltsfoot lives by cnoice are filled till noon every day with mist and vapour ; and heavy dew is deposited there every night through the summer season. Now, if this dew ^ere aUoweJ to clor the evaporation pores or st >maia on the lenses of coltsfoot, the plant would not be able to raise water or proceed with its work except for per- haps a few hours daily. To prevent this mis- fortune, the under side of the leaves is thickly covered with a white coat of wool, on which no dew forms, and off which water rolls in little round drops, as yov. have seen it roll off a serge 10MB KiAilY BlOOEAPBlBf. 9U table-cloth. By this ingeuioug derioe the colts- foot manages to keep its evaporation pores dry and open, iu spite of its damp and moisture- laden situation. One may lay, indeed, that ovory point in the structute of every plant has thus some special purpose; indeed, one large object of the study of plants is to enable uc to understand ana explain such hidden purposes in the economy of nature. During its early li^o, once more, the voung plant of coltsfoot is constantly engaged, like the whitlow-grass and the agave, in laying by material ior its future flowerlijg season. But it does not ^ay by, as they do, in its erpanded it^ aves or other por'.ions of iU body visible above ground ; instead of thnt, it puts forth a creeping underground stem or root-stock, which pushes its way sideways through the tough clay soil, often for several feet, and sends up at intervals groups of large roundish leaves, such as I have already described, to work above ground for it. You might easily take each such group for a separate plant, unless you dug up the root- stock and saw that they were really the scattered foliage of one subterranean stem, which grows horizontally instead of upward. During the summer the coltsfoot lays by in this buried foot-stock quantities of rich materiil for next year's leaves and for its future flowers. In winter the leaves die down, and you see no*- a trace of the plant above ground. 6ut in very early spring, as soon as the soil thaws, certain special buds begin to sprout on the underground stemi and send up tah naked scapes or flower- 212 THE STORY OF THE PLANTS. Hi lit rf H life stems, usually growing in tufts together, and each crowned by a single large fluffy yellow flower-head. These stems are covered below by short purj^lish scales ; and their purple colouring matter enables them to catch and utilise to the utmost the scanty sunshine that falls upon iihe plant in chilly March weather. For this particular colouring matter has the special properfy of converting the energy in rays of light into heat for warming the plant. The scape is also wrapped up in a sort of cottony wool, which helps to keep it warm ; and the unopened flower-head turns downward at first fot still further safety against chill or injury. These various devices enable the colts- foot to blossom earlier in the season than almost any other insect-fertilised flower, and so to monopolise the time and attention of the first flower-haunting March insects. Coltsfoot is a composite by family; so its flowers are collected together into a head, after the ancestral fashion, and enclosed by an in- volucre which closely reaembles a calyx. But the type of flower-head differs somewhat from that in any of the composite plants I have hitherto described for you, because its outer florets are not flat and ray- shaped, but strap -like or needle-shaped. The inner florets, however, are bell-shaped, and much like those of th'^ common daisy. The naked scapes, each re- sembling to the eye a shoot of asparagus, and each crowned by a single fluffy yellow flower-head, are familiar objects on banks or railway cuttings in the first days of spring ; I have known them BOME PLANT BIOaRAPHIBS. 213 open as early as the 12th of January, in sunny weather. But they grow entirely without leaves, and are produced at the expense of the material laid up in the undergrouad stem by last season's foliage. They blossom, are fertilised, set their seeds, turn into heads of white feathery down, and produce ripe fruits which blow away and get dispersed, all before the leaves begin to appear at all above the soil. Thus you never can see the foliage and flowers together; it is only by close observation that you can discover for yourself the connection between the heads of yellow flowers which come up in early spring, a,nd the groups of large angular woolly leaves which follow them in the same spots much later in the season. The life-history of the coltsfoot introduces us also to another conception which we must clearly understand if we wish to know anything about many plant biographies. I have said already that parts of one and the same coltsfoot plant inight easily be mistaken for separate indi- viduals ; and, indeed, if the stem gets severed, particular groups of leaves may live on as such, in two or more distinct portions. This leads us on to the consir'eration of a great group of plants like the common wild strawberry, in which a regular system of subdivision exists, and in which new plants are habitually pro- duced by offsets or runners, as well as by seed- lings. Such a method of increase is to some extent a survival into higher types of the primi- tive mode of reproduction by subdivision. A strawberry plant grows in the first instance 214 TRB STOBT OF THB PLANTS. from a seed, which y^as embedded in a carpel or seed-like fruitlet on the ripo red swollen recep- tacle which we commonly call a strawberry. This seed germinates, and produces a seedling, which puts forth small green leaves, divided into three leaflets each at the end of a long and slender leaf- stalk. As it grows older, however, besides its own tufted perennial stem or stock, it sends out on every side long branches or runners, which are in fact horizontal or creeping stems in search of new rooting places. These stems run along the ground for some inches, and then root afresh. At each such rooting- point, thfe plant sends up a fresh bunch of leaves, which gradually grows into a distinct colony, by the decay of the intermediate portion or runner. Again, this new plant itself in turn sends forth runners in every direction all round it ; so that often the ground is covered for yards by a net- work of strawberry plants, all ultimately derived from a single seedling. Theoretically, we must regard them all as severed parts of one and the same plant, accidertally divided from the main stem, since only the union of two different parents can give us a totally distinct individual. But practically they are separate and indepen- dent plants, competing with ono another thence- forth for food, soil, and sunshine. A great many plants are habitually propagated in such indirect ways, as well as by the normal method of flowering and seeding, indeed, it is diUcult to separate the two processes of mere growth, as shown in budding or branching, and reproduction by subdivision, as shown in the BOMB PLANT BIOGRAPHIES. 21fi springing of Baplings from the roots or stem, the production of runners, the division of bulbs, and the rooting of suckers. I will therefore give here a few select instances of these frequent incidents in the life-history of various species. The tiger-lilies of our gardens produce little dark buds, often called bulbils, in the angles of their foliage leaves. These buds at last fall off and root themselves in the soil, forming to all appearance independent plants. Much the same thing happens with many English wild- flowers. For example, in the plant known 'as coral-root (allied to the cuckoo-flower) little bud- bulbs are formed in the angles of the leaves, which drop on the damp soil of the woods where the plant grows, and there develop into new individuals. In this last-nf^med case the plant seldom sets its fruit at all, the reproduction being almost entirely carried on by means of the bulbils. Such instances suggest to us tLa pregnant idea that a seed is nothing more than a bud or young shoot, 'o whose making two separate parents have contributed. There is, in short, no essential difference between the two processes of growth and reproduction. Again, in the common lesser celandine the root-stock emits a large number of tiny pill-like tubers, which grow and lay by rich material underground (derived from the leaves) during the summer season. In the succeeding spring, however, each of these tubers develops again into a separate plant, in a way with which the familiar instance of the potato has made us familiar. In the crocus, once more, and many ■r I i) !| !1 216 THE STORY OP THB PLANTS. other bulbous plants, several small bulbs are pro* duoed each year by the side of the large one, and these smaller bulbs are of course, strictly speak- ing, mere branches of the original crocus-stem. But they grow separate at last, by the decay or death of the central bulb, and themselves in turn produce at their side yet other bulbs, which become the centres of still newer families. We may parallel these cases with those of trees whose boughs bend down and root in he ground so as to become in tirae independent individuals ; or with runners like those of the strawberry and the creeping buttercup, which root and grow afresh imto separate plantlets. Sometimes still more curious things happen to plants in the way of reproduction by sub- division. There is an English pondweed, for example, which grows i shallow pools liable to be frozen over in s* /ere winters. As cold weather approaches, tne top of the growing shoots in this particular pondweed break off of themselves, much as leaves do at falling time. But they break off with all their living material still preserved within them undisturbed; and they then sink and retire to the unfrozen depths of the pond, where they remain unhurt till spring comes round again. This is jast what the frogs and new»« and other animal inhabitants of the pond do at the same time, to pre' 3nt getting frozen. Next year the severed tops send out roots in the soft mud of the bottom, and grow up afresh into new green idweeds. It is therefore impossible to make any broad line of distinction in this way between what may SOME PLANT 6I0QRAPHIE8. 217 beoonsidered as modes of individual persistence in the self-, a- v^ plants, and what may be regarded as mode , -i* 'eproduction by subdivision. Some plants, like oouch-grass and elm, are almost always surrounded by young shoots which may ultimately become to all intents and purposes independent individuals ; while others, like corn-poppy or Scotch fir, never produce any off- sets or suckers. In the meadow orchids each plant produces every summer a second tuber by the side of the old one ; and from the top of this tuber the next year's stem arises in due time with its spike of flowers. Here we may fairly regard the tuber as a simple means of persistence in the plant itself ; there is nothing we could possibh' call reproduction. But in many lilies the older bulbs produce numerous small branch bulbs at their sides; and these younger bulbs may become practically indepen- dent, each of them sending up in the course of time its own stem and its own spike of flowers. Even when the main trunk of a tree is dead, through sheer old age, it often happens, as in tiie elm and birch, that the roots send up fresh young shoots, which may grow again, and prolong the life of the plant indefinitely. In stone-crops and other succulent herbs, which grow in very dry and desert situations, the merest fragment of a stem, dropp^jd on moist sol?, will send out roots and grow afresh into a new individual. Cactuses and other desert plants have often to resist immense drought, and therefore possess extraordinary 218 THE STORY OF THU PLANTS. vitality in this way. They will grow again from the merest cut end under favourable conditions. These few short hints as to the life-history of various plants in different circumstances will serve to show you how vast is their variety. Every plant, indeed, has endless ways and tricks of its own; and every point in its structure, however unobtrusive, has some purpose to serve in its domestic economy. Thus the ivy-leaved toad-flax, which grows on dry walls, has straight flower-stalks, which become bent or curved when the flowering is over. Why is this ? Well, the plant has acquired the habit of bending round its flower- stalk after the blossoming season, because it cannou sow its seeds on the bare stone, so it hunts about diligently for a crevice among the mortar into which it proceeds to insert its capsule, so that the seedlings may start fair in a fit and proper place for their due germination. So, too, the subterranean clover, growing on close-cropped hillocks much nibbled over by sheep, where its pods of rich seeds would be certainly devoured if exposed on a long stalk like that of other clovers, has developed a few abortive corkscrew- like blossoms in the centre of its flower-head, by whose aid the whole grcap of pods burrows its wayj spirally into the soil beneath ; so th: t the plant thus at once escapes its herbivorous enemies, and sows its own seed for itself auto- matically. It would be impossible in our space to do more than thus briefly indicate by two or three examples the immense number and variety of these special adaptations. Every plant has BOMB PLANT BIOGRAfHIBB. 219 hundreds of them. There is not a tiny hair on the surface of a flower, not a spot or a streak in the blade of a leaf, not a pit or depression on the skin of a seed, that has not its function. And close study of nature rewards us most of all for our trouble in this, that it reveals to us every day some delightful surprise, forces on our attention some hitherto unsuspected but romantic relation of structure and purpose. I will mention but one more case as a typical example. There exists as a rule a definite relation between the shape and arrangement ol the leaves in plants, and the shape and arrange- ment of the roots and rootlets, with regard to water-supply. Each plant, in point of fact, U like the root of a nouse as respecto the amount of rain which it catches and drains away ; and it is important for each that it should utilise to the utmost its own particular supply of drainage or rain water. Hence you will find that some plants, like the dock, have large channeled leaves, with a leaf-stalk traversed by a depres- sion like a drainage runnel : plants of this type carry off all the water that falls upon them towards the centre, inwards. But such plants have always also a descending tap-root, which instantly catches and drinks up the water poured by the drainage system of the leaves towards the middle of the plant. In other plants, again, however, with round leaf-stalks and outward pointed leaves, the water that falls upon the foliage drains outward towards the circum- ference ; and in all such plants the roots, in- stead of descending straight down, are spread- ih :ii 220 THE STORY OF THE PLANTS. ing and diffused, so as to go outward towaidg the point where the water drips on them. Moreover, in this latter case it is found, on digging up the plant carefully, that the ab- sorbent tips of the rootlets are clustered thickest about the exact spots where r.he leaves habitually drop the water down upon them. Every plant is thus to some extent a catchment- basin which utilises its own rainfall : it collects rain for itself, and conducts it by a definite system of pipes and channels to the precise spots in the soil where it can best be sucked up for the plant's own purposes. On the other hand, while every part of every plant is thus minutely arranged for the common advantage, every species of plant and animal fights only for its own hand against all comers. Nature is therefore one vast theatre of plot and counterplot. The parasites prey on the vegeta- tive kinds ; the vegetative kinds respond in turn by developing checks to counteract the parasites. The squirrels produce sharper and ever sharper teeth to gnaw through the nutshells ; the nut- trees retaliate by producing for their part thicker and ever thicker shells to baffle the squirrels. And this play and by-play goes on unceasingly from generation to generation ; because only the cleverest squirrels can ever get enough nuts to live upon; and only the hardest-shelled and bitterest -rinded nuts can escape the continual assaults of the squirrels. In order, therefore, really to understand the structure and life of any one species, we should have to know in the minutest detail all about its native conditions. THB PAST niSTORT OF PLANTS 221 its soil, its surroundings, iM allies, its hired friuiids, its blackmailing foes, its exterminating enemies. Such exhaustive knowledge of the tiniest weed is clearly impossible ; but even the little episodes we can pick out piecemeal are full of romance, of charm, ac^ of novelty. CHAPTER XIV. THE PAST HISTOr.Y OF PLANTS. I PBOMiSED some time since to return in due season to the question why plants, as a rule, exhibit distinct kinds or species, instead of merging gradually one into another by imper- ceptible degrees. This problem is generally known as the problepa of the origin of species. You might perhaps expect (since plants have grown and developed, as we have seen, one out of the other) that tney would consist at present of an unbroken series, each melting into each, from the highest to the lowest. This, however, is not really the case ; they form on the contrary groups of distinct kitids : and the reason is, that natural selection acts on the whole in the oppo- site direction. It tends to make plants group themselves into definite bodies or species, all alike within the body, and well marked off from all others outside it. Here is the way ti-^s arrangement comes about. As situations and circumstances vary, a form is at lac' arrived at in each situation T7hich approximately fits the particular eiroum 222 THE 8T0HT OF THB PLANTS. fe t, . is ll stances. This form may perhaps vary again in other situations, and give rise to individuals hotter adapted to the second set of circum- stances. But just in proportion as such in- dividuals surpass in adaptation one another will they live down the less adapted. Hence, the intermediate for^rR will tend to perish, and the world to be filled m the end with groups of plants, each distinct from others, and each relatively fixed and similar within its own imits. At all times, and in all places, this process o.' variation and adaptation is continually going on ; new kinds are being formed, and inter- niediates are dying out between them. For the intermediates are necessarily less adapted than the older form to the old conditions, and than the newer form to the new ones. Moreover, when any great point of advantage is once gaiLed by a kind, it tends to go on and be preserved, while variations in other parts continue uninterrupted. Thus, the first com- posite plant (to take a concrete example) gained by the massing of its flowers into a compact head : and it then became a starting-point for fresh developments, each of which maintained the massed flower-head, with its ring of united stamens, while adding to the type some fresh point of its own, which specially adapted it to a particular situation. So, too, the first peaflower gained by the peculiar form of its oddly-shaped corolla, and therefore became the ancestor of many sv,^ arate kinds, each of which retains the general pea-like type of blossom, while differing ¥RB PAST BIBTOBT OF TLANTS. 92d in other reHuects as widely from its neigh i)ourt as gorse and clover, peas and laburnum, broom and vetches, scarlet -runners and lupines. A group of kinds, so derived from a common pro- genitor, but preserving throughout one or more of that progcr itor's peculiarities while differing much in other respects among themselves, is called a family. Thus we speak of the family of the paaflowers, the family of the roses, the family of the lilies, the family of the orchids. KM.ch family may incJade several minor groups, known as genera (in the singular, a genus) ; and each such genus may further include several distinct kinds or species. For example, all the peaflower family are dis- tinguished by their possession of a peculiar blossom whose corolla consists of a standard, a keel, and t.vo wings, like sweet-pea or broom. This family contains several genera, one of which is that of the clovers, incl'^^ing certain peaflowers which have learned to mass thei» blossoms into a roundish head, and have trefoil leaves, and very few seeds in the short see'^ )d. The clovers, again, are subdivided into speoct. or kinds, such as purple clover, Dutch clover, hop clover, and hare's foot clover ; in Britain alone, we have twenty-one such distinct species or kinds of clover. You will see at once that this method of grouping by ancestral forms enables us largely to reconstruct tha hist'^ry of each particular plant or animal. Why don't these kinds cross freely with one another, and so produce an endless set of puzzling hybrids ? Well, they do occasionally ; SSI THB BTOHT Of TUB PLANTS. and such mon^el forma often sLow ui every g>i8ibl6 variation between ihe two parents, ut this can on'y happen when the parent atocks are very close to one another; and even then, the hybrids tend to die out rapidly. Why? Because each of the parents is better adapted to a particular situation ; the hybrid usually falls between two stools, and gets killed down accord- ingly. It cannot stand the competition of the Irue spemes. New kinds, however, may some- times take their rise from chance hybrids, which happen to possess some combination of advantage- . Thus plants in the mass, as we see them around us at the present day, are divisible into several w oil- marked groups, some of which are now dominant or leading orders, while others are hardly more than mere belated stragglers or loitering representatives of types once con^mon, but now outstripped in the race by younger competitors. I cannot close withont" briefly describing to )^\i the main divisionB of such orders or i^.oups, as now accepted by modern botanists. The widest distinction of all be-ween plants is that which marks off the simpler and earlier forms, which are wholly composed of ceils, from the higaer and stem-forming types, which are also provided with systems of vessels and woody tissue. The first class is known as Cellule h Plants ; the second class as Vascular Plants. These are the greatest and most general divisions. THi run iiiiiTORY or plaktb. The CblluuAR Plants coniprige many sorts, from the simple oae-o«lled typos whion float freely in water, up to the relatively high and oomDlex seaweeds, which produce large fleshy fronds, and often display a conuiderable division of labour between their various parts and orsans. Still, as most of them live in water, either oresh or salt, and wave freely about in the liquid that surrounds them, they have no need of an elabo- rate system of conducting vessels, because every part can drink in water and dissolved food-salts from the neighbouring pond, sea, or river. Still less have they any necessity for a woody stem, which would only be a disadvantage to them in stormy weather. Hence most of the cellular plants (with certain exceptions to be noted here- after) are water- weeds ; while most of the vascular plants (with other exceptions to be similarly created) are land plants. In particular trees and shrubp, the highest forms of plant life, are invariably terreitrial. Various successive stages of these cellular plants may be briefly described in rough out- line. First of all we get the simple one-ooU'^d plant, the lowest type of all, consisting of a single mass of ^.rotoplasm, generally with chlorophyll, surroundbv" by a cell-wall. Next above these come the hair-like water-weeds, which consist of rows of such simple cells, placed end to end in single file, one in front of another, like pearls in a necklace. These kinds are many-celled, but each cell is here in contact with two others only, one below, and one above it. Thirdly, we ^dt the flat leaf-like wAt«»^. 226 THB 8T0RT OF THB PLANTf.. weeds, which have thin green ironds, oomposed of a single broad sheet o^ cells, not a hair-like row ; each cell has here many cells around it, but all lie in one plane ; the sheet is only one cell thick ; it does not spread abroad in more than two directions. Lastly, we get the ordi- nary thick-fronded seaweed, in which sheets of cells, many layers deep, grow in divided masses on rope-like bases, and closely resemble to the eye true vascular plants with stems, leaves, and branches. Most of these cellular plants, when they posses^ green chlorophyll, are known as algcB. There are several low forms of plants, how- ever, which do not possess chlorophyll, but live at the expense of other plants, exactly as animals do. These re generally known in the lump m fun^i. Many of them are terrestrial. The distinction, however, is not a genealogical one. Cellular plants of various grades have often taken, time after time, to thic lower parasitic or carrion-eating habit; and though they therefore resemble one another externally in their absence of green colour, in their usual whiteness and fleshiness, and in their mush- room-like substance, they do not really form a natural class ; their resemblance is due to their habits only. In short, we call any cellular plant a fungus, if instead of supporting itself by green cells, it has adopted the trick of living on organised material already laid up by other plants or animals. Among these fungus-like plants, again, some of the simplest and lowest are the celebrated THK PAST HIBTOBT OP PLiiNTS. 237 bacteria t which are oiie-<^lled orffanisms, living in stagnant or putrid fluids, and also in the bodies and blood of diseased animals. They answer among fungi to the one-celled algcs. Many of them cause infectious diseases; such are the baoilU of diphtheria, typhuB, cholera, consumption, small-pox, and influenza. Sur- rounded by eb suitable nutritious fluid, these tiny parasitic plants increase with extraordinary and fatal rapidity. Though they are really one- celled, and reproduce by cell-division, they often hang together in rude lumps or clusters which simulate to some extent the many-celled bodies. In this book, however, where we have concen- trated our attention mainly on the true or green plants, I have not thought it well to dwell at any length on the habits or struotrre of these animal-like organisms. Another well-known group of small fnngos- like plants is that which contains the yeast- fupgus, a one-celled plant, whioh reproduces by budding. The higher fungi are many-celled, and often possess well-marked organs for different pur- poses. They answer rather to the seaweods and higher algcs. Familiar examples are the common moulds, which form on jam, dead fruit, and other decaying material. Some of them, like the smut of wheat and oats, €;.re parasitic on growing plants, and most dangerous enemies to green vegetation. The highesb fungi are the groups which include the mushroom, the puff-ball, and all those other large and ouriously-shaped forms commonly lumped to- 328 THE STORY OP THE PLANTS. gether in popular language under the name of toadstools. Their anatomy and physiology is extremely ^ .mplex. To recapitulate ; Cellular Plants belong to two main types ; those which contain chlorophyll, and live like plants by eating and assimilating carbon under the influence of sunshine; these are generally grouped together in a rough class as ALGJB : and those which contain no chlorophyll, but live, like animals, by using up or destroying the carbon-compounds already stored up by green plants ; these are generally grouped to- gether in a rough class as fungi. The lichens form a curious mixed group, whose strange habits cannot here be described at any adequate length ; they are not so much separate plants as united colonies of algae and fungi; in which the green alga does the main work of collecting food, while the parasitic fungus, increasing witb it at the same rate, eats it up in part, while contributing in turn in various ways to the general good of the compound community. This is therefore hardly a case of pure destructive parasitism, but rather one of a co-operative society banded together on pur- pose for mutual advantage. The mosses and liverworts, once more, show us an intermediate stage between the true cellular and the true vascular plants. They have a rudimentary stem, and beginnings of vessels. They have also leaves, or organs equivalent to them ; and they display the first approach to something like flowers. THE PAST HISTORY OF PLANTS. 229 The Vascular Plants, again, which are characterised by the possession of special vessels for the conveyance of sap and organised material, and by the presence of more or less woody fibres, are divisible into two main groups — iheflowerlesst and the flowering. The flowerless group of Vascular Plants are mainly represented by the ferns and horsetails. These were at one time the leading vegetation of the entire world, far outnumbering in kinds all the rest put together. But they have now been Uved down by the flowering plants, which at present compose the main mass of the plant aristocracy. The flowervng plants^ once more, fall into two main groups ; the small but widespread group of naked-seeded plants, including the cycads, pines, firs, cypresses, and yews; and the very large group of fruit-bearing plants, including almost all the kinds of herb, shrub, bush, or tree familiarly known to you, as well &8 almost all those various plants with which we have busied ourselves in this little volume. You will thus see that the vast majority of sppcies in the vegetable kingdom belong to small and relatively inconspicuous orders. Indeed, for the most part, we habitually disregard the cellular plants, thinking only of the vascular ; while among the vascular themselves, again, we disregard - the flowerless, thinking only of the flowering; and amon:' the flowering kinds, we concentrate our attention as a rule on the fruit-producing group (in the botanical sense of the word) and neglect the naked- seeded. In short, we usually confine 330 THB 8T0RI OF THB PIiANTS. our attention to the highest division el the highest groap of the highest half of thr^ vegetable kingdom. The rest are for us mere inconspioa- ous mosses, moulds, or seavyeods. The fruit-producing group of flowering plants are finally divided into the dicotyledom and the monocotyledons f whose chief differences I have already pointed out to you. And to complete our picture of this iTifinite hierarchy, the dicoty- ledons, once more, are divided into various families, such as the buttercups, the roses, the orucifers, the composites, the labiates, the umbellates, the saxifrages, and the oatldn- bearers. The buttercup family, in particular (to select a single group), is further divisible into genera, such as buttercup, marsh marigold, larkspur, anemone, clematis, and aconite ; while the buttercup genus {iO take one only among these) comprises in turn a vast number of species, such as the water-crowioot, the ivy- leaved crowfoot, the meadow buttercup, the bulbous buttercup, the lesser celandine, the goldilocks, and so on for pages. Similarly, the monocotyledons are divided into various families, such as the orchids, lilies, grasses, and sedges : the families are divided into many genera ; and each genus into several species. The ic^nite variety of curoumstancee is such that each type goes on varying and varying for ever io order to fit itself for the endless situations it is called upon to fill, and the endless diversity in the accidents of olimate or soil or position that it may chance to come across. Thus we have in England more than a hundred different kinds of ■THR PAST HISTOBT OF PLANTB. 381 gmssds, each specially adapted for some one partioular aitnation. Only the closest individual study can give any adequate idea of this immense diversity of plants in nature. The geological history of the world shows us that the development of plants has been slow and progressive. In the earliest rocks (of which an account is given in ar other volume of this series), we get few traces of any plants hut the lowest : so that at that time it is probabh none but seaweeds and their like existed — cellular plants which contain hardly any parts solid enough for preservation. By the age when the coal was hid down, however, ferns, horsetails, and many gigantic extinct plants with solid stems fc^ad begun to exist ; but few or no flower- ing plants, except conifers, had yet been de- veloped. Later still came the true flowering plants, with covered seeds, at first in simple and antiquated forms, but becoming mure complex as birds, mammals, and flying insects of the flower-haunting types were developed side by side with them to visit and fertilise them or to disperse their seeds. Succulent fruits, of course, could only arise when tribes of fruit-eaters had been evolved to assist them ; while such special bee-fertilised types as the sage group, and such complex forms as the ori^hids and composites, requiring- the aid of higLly- developed insects, are of extremely recent evolution. Plant and animal life have continually reacted upon one another mim 989 TRV 8TOBT OF THS PLANTl. Whoever has heen interested in the study of plants by this little book may be glad to know what is the best way of continuing his acquaint- aiije with the subject in future. Nothing gives one such a gra^ip of the facts of botany and of life in general as careful study of the plants which giow in one's own country. Students in the British Isles should therefore buy a copy of Bentham and Hooker's British Flora, and seek by the aid of the key at its beginning to identify for themselves every flowering plant they come across in our woods and meadows. American students should get in like manner Asa Gray's Manual of Botany. In the course of identifying all the plants you find, you will begin to understand the nature of plant life and the course of plant evolution in a way that is quite impossible through any mere book-reading. Buy also a simple platyscopic lens, and a sharp penknife to assist you in dissection. Armed with these simple but useful tools, you will soon make rapid and solid progress in the knowledge of nature. For further and more detailed information on the laws of plant life, you cannot do better than consult Kerner and Oliver's Natural History of Plants, which sets forth in full an immense number of interesting and curious facts, in language comprehensible to any attentive and careful student. * cy UNWIN BBOTHEBS, LIMITED, FBINZEB8, WOKING AND LONDON. ^ of low int- ing iny the ;ry. ore Hsh its ery ods get In nd, ant v&y ere ipic in iful ess on lan 0/ nse in ind ON.